I usually just get on ebay and get one of the adapters that lets you put a regular bike water bottle holder on the handlebar. but I guess that would limit the kind of bottle you can use, like I don't use a coffee cup, or a beer/pop can.
(i don't know though. don't drink beer or buy pop in cans, at least when I'm riding around. maybe it would fit)
I always buy the Gatorade that looks like a bike water bottle 'cause I can buy them for a dollar at several dollar type stores (the twist top on them is nice for riding too), or a Mexican soda I like that fits in it also.