I've heard there are rules for multiple varieties of alchemy in Art & Academe, The Mysteries Revised Edition, and Hedge Magic Revised Edition. I'm wanting to play an alchemist, Hermetic or otherwise, and in particular I want to be able to make a homunculus. So do any of the alchemist variants have homunculus-making as an option? I'm asking so I know which book to buy. I mean eventually I'll want all the books, but I want to buy the one that can make my concept work first since I'll need it soonest.

So yeah, do any of them (or a different book I haven't heard of) have rules for an alchemist making a homunculus?

The answer is, ultimately, contingent on what exactly you want your 'homunculus' to do. Care to clarify?

There is a Flaw, "Homunculus Wizard", in RoP: F that gives the magus a homunculus that he must feed with his blood everyday to retain his Gift, but it's a rather specific application and might not be appropriate to your concept.

More conventionally, you might consider snagging RoP: M and creating one as a 'Magic Thing' such as the Mandrake homunculus described on page 30 of that book. Though the process is effectively taking a familiar...

The closest thing to "alchemical creation of a homunculus" in Ars Magica is the Mandrake above, particularly with a Learned Magician (Hedge Magic Revised) possessing the Mythic Alchemy Virtue so that he can use vis. Even that, though, requires a rather generous SG, and wouldn't be very effective since Mythic Alchemy doesn't use the Learned Magician's Arts (annoyingly enough).

Even then, though, you're not "creating" a homunculus, you're taking a mandrake root and binding it as one, so... Probably a no-sell.

The Mysteries Revised probably won't help you either, since the closest it gets to the concept of homunculi is that a pre-existing Familiar can become "an alchemical magical beast" if you spend extra vis on it while creating and using the Greater Elixir to become immortal.

Really, creating beings with Might is high-end and/or difficult-to-achieve stuff. Magi can do it as a CrAn(Vi) Ritual with a minimum level of like 55, which might almost match what you're after except that most depictions of homunculi don't have their minimum strength as "equal to a typical dragon." (Also, it's a stretch to call anything produced by vanilla Hermetic magic a feat of alchemy, even if your magus is crazier than usual.) The alternatives are things like the Automata of the Verditius, which are non-sentient but lifelike machines, and the Awakened Devices of Heron, which are also machines in the shape of living beings, but sentient this time.

Golems are done by Mythic Companion: Kabbalist. Since it does not require the Gift, you could reskin it.

Fourth Edition had rules for this, presented in WGRE (Wizard's Grimoire Revised Edition). Perhaps you could adopt something from that?
However, it does not involve alchemy (other than Hermetic Magic), and is not accessible for a hedge wizard.

And I believe, in the second edition (or was it third), the supplement on Faerie describe a process to make an homonculi.
Basically, it involves finging a whole mandrake root, harvesting it without damaging it (and without getting killed by its shriek). Once done, the mandrake root is fed by the blood of the magus for a season, then awaken as little character, speaking naturally all the languages of his "parent", and with an innate knowledge of magic - although it cannot cast spell itself. An homonculus is quite jealous, therefore it cannot stand the presence of a familiar - the magus has to choose.

The "Homonculus wizard" of RoP:Faerie is a very nice concept, although because of its design, the homonculus cannot really be played - it cannot be seen by anybody but the magus, otherwise it dies. So it really limits the potential as a character since its interaction are very limited.

An alternative could be to use a combination of virtues & flaw and reskin them to fit a "homoncule wizard".

For example:
"Intuitive magic"
Faerie friend (minor flaw)
Puissant MT (minor virtue)
Minor focus (minor virtue)
Necessary condition (Major flaw)

Faerie friend is reskinned into Magical friend - it works exactly the same ways, except that the homonulus is from the magical realm and not the faerie realm.
Puissant MT: reflect the contribution the homonculus brings to the magus - obviously, the homoncule must be nearby for the magus to benefit from it
Minor focus: to be determined, but again reflect the contribution of the homonculus to the mage's magic. The homonculus strengthen the mage's connection to the magical realm for some very specific spells.
Necessary condition: the mage cannot cast spell without the homonculus being nearby.

Other possible combinations:
Age quickly (major flaw): the homonculus drains the life force of his master.
Magical memory (minor virtue): the homonculus remembers everything done in the lab.
Free study, Inventive genius (both minor virtues): the advice of the homonculus in the lab is always spot on.
This set of virtues & flaws are more suited for a more "academic" homonculus compared to the previous one.
And to reflect and homoculus who served another master before, you might even consider fitting in "Ghostly Warder" - the homonculus is always invisible or incredibly tiny instead of being ghostly.

The advantage of using existing virtues & flaws and reskinning them is that it is easy for your ST to approved it since they are coming from the core book. Mechanically, they have been tested, they work and they are somehow "balanced". Depending on your ST, you can negotiate if you only needs to pay the final value, or each and every virtues/flaws. In the first instance, it cost a major flaw and a minor virtue, and the latter, it is worth two minor virtues, a minor flaw and a major flaw. The first instance "save" you a slot on minor virtue and flaw. Just be reasonable, and it should be fine.

If your want you magus to acquire an homonculus during the course of the game, you can inspire you from the Mysterie initiation script. Remove the need for cult and a mystagogue, but instead the initiation script becomes a procedure to acquire an homoculus. Design trials and requirement as per a initiation script: finding a whole mandrake root in a magical aura (difficult challenge), consumption of blood and virtues to awaken the mandrake root (sacrifice of virtus, possibly minor flaw linked to the blood sacrifice), then design the package of virtues & flaws that will be granted by the homoculus to gauge the "final value" of this new virtue (and use some common sense not to abuse the system), add a few extra steps to balance everything out - possibly sacrifice of a familiar. And here you got your recipe for homoculus.