You'll probably have to get it from someplace that sells race fuels. You used to be able to get it from chemical supply places and other suppliers but that's more difficult now because of the really tight controls on the chemicals used in meth production. Everyone still has it, but it's not as easy to just walk in and buy it. Not as bad as cold/flu medicine though, which practically requires a background check and 5 day waiting period to buy these days.

If you only need a little you can buy fuel line antifreeze from a parts store, which is somewhere close to 100% methanol. Some brands of windshield washer fluid work really well for water injection systems too.