There is synthetic mescaline and it isn't necessarily that expensive - I know this from personal experience, had it lab-tested and I tripped two times on it thus far... but yes it is relatively rare, though it may have a better market nowadays with the advent of a 'certain network'.
Still, test it by titrating a dose (at the very least try it at a couple mg, then 25-50 mg before jumping to 500), because it is possible you got something else. Even if it is active at the dosage range it should be it is still possible someone mixed another much cheaper phenethylamine with an inert powder.
Don't take more than 500 mg for a first time. That you had bad luck in the past doesn't mean you should overdo it. Don't expect it to be wildly hallucinogenic, in my experience mescaline just doesn't tend to have the mindfucks and warping but instead is calmer and more visionary (showing you things when you lie down with your eyes closed). Hoping for something it just isn't will only disappoint you which would be a shame since mescaline has it's own sublime charm if you are just open to appreciate it.
The plan to drink a watery solution over the course of half an hour is fine - I've done that - but no need to make the water warm or tepid, that will just make it more revolting. Mescaline should dissolve okay, and you can always stir a bit extra.
Capsuling also works (did that another time with crystals from a different source), but I would recommend spreading the dose over 3 parts spaced again over like half an hour.
Don't snort it, it's way too much and I doubt it would even help.
Personally I think coke and psychedelics are a disgusting mix, a psychedelic trip is beautiful because it shows you something beyond your myopic ego but drugs like coke mostly inflate your ego, your confidence and self-involvement. IMO save it for a totally different day. Just smoke some weed if the trip turned out disappointing.
Here is our subthread specifically for synthetic or at least purified mescaline (rather than cactus / alkaloid mix):
http://www.bluelight.ru/vb/threads/...escaline-Dosage-amp-Methods-of-Administration
It will be merged later.
(P.S. the solvent is called D-limonene)