I don't know where you can get poker chips, but I have researched medals and stamping planchets (blank rounds).
Not as expensive as you'd think, unless you pick a base metal like silver, of course.
I would figure that poker chips could be much cheaper.
Looking at Alibaba, they are pretty comparable to medals/coins.
A bit cheaper than medals/coins, but medals/coins would be kind of cool to play with at a table, especially if grooved for stacking, as they can make a nice sound when you toss them in the pot.