If I was your GM, I'd probably disallow fleshcrafting.
Particularly in the case of a PC willing to go against the spirit of the rules as blatantly as someone who would copy deathless like that.
You can't
Prerequisites: Caster level 10th, 5 or more ranks in Craft (alchemy).
From the prices, I think he is going to buy it from some nebulous "friend of a friend of a friend's second cousin twice removed that was a 10th level drow wizard" or some general open market. I can somewhat see the possibility of these having a black market as much as any other magical item.
I also somewhat like the idea of fleshcrafting myself. It would prevent some of the multiclassing some characters have to go through to get natural weapons. Ignoring the first one, since he acknowledges it as a joke, the ones with humanoids seem alright, especially since they already exist as basic traits for races already allowed for players. The dolphin one might be ok too, since it is a relatively small alteration that mimics a natural phenomenon. As far as a black market goes, I do not even want to consider what the spores potion was originally marketed as. Plus, I find it hard to imagine a player having that without growing plants from their head (which can arguably be bad for interactions with other character).
I do love the idea of a campaign centered around gangs that market in flashcrafting though. With some potions as loot to give to authorities for a bounty type deal, resell, or use themselves. Appropriate reactions from NPCs for body modifications from using some of them too.
I'd say you do have to justify your purchases, especially when you are asking to get items that you shouldn't yet have access too (and alot of them to boot). If fleshcrafting is common and you can buy it in any old market then fine, but it's use is typically restricted in the drow world of the underdark.
Alchemists can't get potions of Greater Magic Fang made by level 20 casters either. At least not in any sane game I've ever played.
Well, it sounds interesting enough that I could see a GM adding a supply route. Just add a dark and troubled past that includes connections to the black market, and see if your GM takes the hook.
Honestly, while you might justify it based on the fact that its use is not widespread, many of the magical weapons he could splurge on do not have lower caster levels. A flaming sword would be within his price range, but it needs caster level 10. Would you complain if the fighter had one? He is a wizard, and he found little use in magical weapons and armor. So why begrudge him the use of interesting magical items?
So I have no idea how the fleshcrafting thing could be balanced... CR is not balanced around individual abilities, but around monsters as a whole package. It is broken by design and a DM that allows blanket flesh-crafting has only himself to blame.
Also, most of your examples except for the plant and dolphin are templates or 0 HD races. The CR of an orc or fetchling is not 1/2, it is "based on hit dice." I could just as easily pick a 20 hd orc to price the abilities off of. In any case I don't think they count as "monsters" and are not valid choices for flesh-crafting.
The link posted by blackbloodtroll has actualy reasonable prices.
It looks like they are just priced as slot-less magic items. So use those numbers.
Can't you just use the 3.5 Grafts in PF? Or are they incompatible somehow?