The premises of the saga would tend to imply the following covenant boons and hooks. Additional ones are expected to reflect the troupe's decisions.
Build points would be around 1000 total, with approximately 300 dedicated to vis sources.
Sounds reasonable. I would also expect some BP not to go to easily transportable stuff based on the premise, as the three immediate heirs already divided those things. But some transportable stuff could be things we bring in, so a good chunk of transportable BP could show up that way. Ultimately that doesn't matter on the purchasing side, more on the flavor/design side.
What is the right? right of transporting goods, right of toll for a bridge, right of an amount of money from the Telsperg family? Sorry if I overlooked something.
I was thinking a better-than-average laboratory that he used when holing up here. It would basically belong to the Heir, but he would probably lend it to the others when he isn't using it. Particularly if there are urgent tasks to be done early in the saga while their personal labs aren't set up yet.
Certainly, several of the mundane specialists would probably be there already, as would a certain amount of silver (from the source of income). Even vis reserves, as any vis produced by the sources would have accumulated while the filii were deciding how to handle the inheritance (the sources belong to the covenant).
Basically, any one of these. The Right minor boon is just saying that this source of income is completely above-board and secure from mundane interference, as the mundane authorities granted said right to the covenant (in this case to the old magus "and his heir").
ahh right, I thought I had misread the explanation of the source 
Hmm...if we want wealth management or rather "10 villages we get money and produce from" to be out of our hands, maybe make the Telsperg family very wealthy and have them be our sponsors - through their agriculture, rights, fairs etc?
By the way, will we be using the BP collectively, or will you jazz up the library, items, specialists etc?
Collectively for the most part.
I will probably design the vis sources so that they integrate well into the setting, but based on the preferences of the troupe regarding Arts and yield of the sources.
In the same way, I can come up with some of the assets that are acquired directly by the covenant (library, lab texts, specialists) before saga start, while each of you arrange for your magus to acquire other assets during your post-Gauntlet advancement. Some of the "collective" covenant resources can still be designed by others than me.
Maybe we should then each get a pretty minor amount of build points each (like 50?) To represent the stuff we end up bringing to the covenant. The remainder (350 I think), we can spend on resources together.
Any particular items or lab texts that we want to have right away? I'm somewhat partial to having an item to cast The Inexorable Search, since that seems to almost always be a useful spell.
A Creo/Corpus Vis source for longevity rituals; Vim for Aegis.
You mean, like all PC covenants? Where's the fun in that? 
Ok, it seems to me that we are shooting in too many directions at a time here, going into details when the basics are not decided upon. So let's try to structure things a little bit.
What is the covenant's basic structure. A stone tower? A villa-style mansion? An underground structure? A collection of smaller buildings with no big central structure?
Keep in mind that all of it would have been set up only a few decades from the saga start. So a big old decrepit gothic like structure is unlikely. At best, there might have been some ruins on top (or beside) of which the new structure was built.
I personally really like the feeling of taking up residence in villa/manor. We could go for renovating one of the old ruins around here as well if we wanted to try and stick with the ancient-structure vibes.
I would think something like a manor house would make sense, as could a single casting to get one tower seeing as the magus had a lot of vis. But I'd like to figure out his purpose first, as that may be reflected in the building he set up.
Meeting allies in secret? - Perhaps some underground stuff.
Stick it to the tribunals around? - Perhaps a tower.
Make something beautiful? - Perhaps a manor.
I think your idea of being able to renovate is key. Whatever we start with, we could always attach something to it, build something beside it, create underground chambers beneath it, etc. So it's not that critical for our magi's work. Just start with what seems most fitting and we'll work from there.
Note that it can be a combination of structures (I like the idea of a manor house built against a cliff, with some caves behind it).
Same thing with the reasons for establishing a secondary sanctum here - he could have been investigating traces of a hedge tradition in the region and set up some family (either blood-related or adopted) at a safe distance from his enemies and to harvest his vis sources for him.
Many possibilites there.
I'm trying to work off of this to see if I can get some good momentum going in this direction... What if this Jerbiton grew up here in this valley. He returned out of nostalgia; that's why he chose here of all places to make beautiful. He could have made an agreement with the local rulers (the knights) that he would work to improve the area, from which they could then profit, if he would have a place to build. Or, if it's just a smaller house, he could have just built the place on a plot of land without needing really special permission.
I was thinking similar: a manor house built over (to hide) a cave entrance, with caves underneath it. Great minds think alike, right?
Yup. I'm in favor of a clear overt thing, such as creating a beautiful place, alongside something more covert which is unknown to the characters at the start.
Though the characters would not know, I'd like the players to be aware of at least the essentials of whatever "covert" element is.
I missed this thread, somehow, sorry about that. Reading through, I had an idea, which may be cool or may be wacky.
What if each magus, or at least each magus who wants to, has a pretty individual sanctum, checking several of those boxes; and we present ourselves as chapterhouses within the various tribunals, as a way of keeping valid claims to the vis sources within each? It could have been set up by the original guy, as a way to keep hold of his vis, but maybe he didn't have a chance to complete recruitment, so ended up passing on the half-finished project to his heir, who has done the recruitment (and found magi with ties to the various tribunals).
So we have a manor house, but we also have some ruins, a tower, a cave, or whatever else seems idiosyncratically interesting to someone. Main library/council rooms in the manor house, of course.
I thought about this too, but it significantly complicates our Aegis of the Hearth if we split up too much.
it can still cover the area of the valley, and just be bigger...
I don't necessarily think we have to go with my idea, but I don't think Aegis is a good reason not to, there are ways to work around that.