It's a reasonable assumption that ignem vis will be in short supply until after the Certamen tournament.
The tractatus is available for sale, under Cow and Calf. And yes, there is more where that came from.
As to the quality, if you inquire directly he indicates that an apprentice who had just had his Arts opened was able to work 1st magnitude mentem spells with some degree of success. (I.e. it's max quality possible, short of transforming it into a book that can't leave a regio).
ALexei is still flush from his victory when he's approached by Fieltarn. "Huh? What is it your asking? Are you asking if I know Lang...Lang...what was his name?" listening closer he realizes what's being asked.
"Oh! I see, Ignem vis." he frowns. "No I'm afraid not, Ignem vis has little use in my arts. But who is this Lang...fellow? Let me speak with him, perhaps I can convince him."
I think I said to match it up to cost in build points. I thought there was an easy conversion, or at least implcitly stated. Here's what I came up with.
Money stocks cost 1 bp for 10 mythic pounds at creation. The cauldron, as a lesser feature is 10 bps, and would therefor cost 100 mythic pounds. It seems excessive, so let's call it 50, and I don't think there's a funding problem.
((Kind of lost this thread for a while))
Charm or Carouse of 2
1d10+2=3
Exploding die 1d10=7 + 2 16 total.
Given Korvin's prior frustrating relationship with the House, or at least the Magical Mercere side of it, he's not up on the current gossip. The prima has been looking for a Magus to tackle the problem of longevity rituals being less effective on mundanes. She's been loath to contact you directly, given Korvin's past. Although, she doesn't have anything to do with where his children were placed, as that is a Magical Mercere matter handled by the most senior Magical Mercere.
Korvin can expect some financing from the House, and possibly and a supply of volunteers for rituals, but that supply is not inexhaustible.
Splitting some hairs mechanically. It could be possible that you are able to invent a LR that is more effective for everyone the divide by 10, rather than 5, in which case, it is of a benefit to the Redcaps without supernatural powers, and no one is the wiser. Or it could be that you invent a LR which is even more effective for those Gifted/Supernatural powers and has the same benefit for mundanes as the currently existing guidelines for longevity rituals. I hope I'm explaining that well enough to make some sense of it.
Nah, I would not take more of your time with such trivial question of vis, as there will probably be more than one opportunity for such exchange later in the day, or tomorrow after the Certamen bouts I guess. Fieltarn then gets a little bit closer to Alexei, and still smiling as if sharing a joke, he whispers quietly : "On the other hand, since you are probably more familiar than I am with House Guernicus - I thought that you might be interested to know that I've had a tail since Eloi recognized our Covenant. I wonder if yourself and our other sodales are not similarly watched, which I'd find a bit... vexing - such apparent mistrust for our going and doings, as if we were some uninvited thieves and not magi in good standing. But being Ex-Miscellanea, I'm probably not the best person to tackle this situation... while you, being our security expert and... of a more respectable status, might be more adequately... err, prepared for this."
A lovely young woman dressed in purple silk makes her way across the room. She brushes a lock of long black hair out of her face, and touches Fiona lightly on the elbow. "Pardon me-- are you Fiona of Domus Ex Miscellanea*? I heard you're looking for tractatus on Mentem?"
[size=85]*This particular style of address is intended to be an unusually polite mode of addressing an Ex Misc.[/size]
Fiona looks down at the woman with an expression of mild surprise. [color=blue]"That, I am. And who may I have the pleasure of speaking with?"
(p.s. & ooc - welcome aboard!)
£50 for the cauldron sounds reasonable.
For the copy of Lycanthropi Londinensis, Fiona will offer one pawn of Muto for it, and subject (of course) to Cow & Calf.
"Muto? Please! Who uses that stuff? I need 8 pawns of Muto."
[color=blue]"Eight? Eight pawns of Muto for a tome of mundane lore?" Fiona snorts her derision. [color=blue]"Two pawns of Rego."
Got a roll to go with that?
Alexei looks a bit bleary eyed at this point between the joust and celebratory drinking. "You know...you're the second one to mention something about Quaesitors watching the events. I haven't seen one yet to my knowledge, I'm new to the area though. Some might know I'm in the Milites though and look to ask for my help as an...a..." he pauses in thought. "What are they called...?" he snaps his fingers and puffs out his chest. "Hoplite! Maybe they're looking for me to help as a Hoplite!"
I know, it can get confusing, Joust is on the last day of events, 5 days from this day. So, maybe you're planning ahead? 
God I hope so. Com 2 + Bargain 3 + die roll of 0. Really? Geez! Okay, botch check comes up a 7, which results in 2+3+0=5. This is a really handy book to have for the covenant, so I'm going to burn a Confidence point on this (which I keep forgetting), so that bumps it up to an 8.
Indeed. Alexei rocks, that's worth a drink or two.
The confidence point is not spent. "4 pawns of Rego." Do a Bargain + Perception roll to evaluate the offer.
It's enough to know that Fiona's getting jobbed. 4 pawns of Rego is inordinately valuable...