If you want bulk here it the place:
http://www.superiorenterprise.com/insectnewprice.htm
Their 4.5 inch 32oz poly-fabric cups are pretty much the standard I think. You have to get 240 of them, but at $73, you can't beat the price. I split the cost with a local dart frogger. I started with Mason jars, but got tired of all the extra steps and the fact that fruit flies get caught under the rim and slowly creep out. Some people reuse the plastic containers although the lids can get kind of dirty after a culture with a lot of production. However, you can also order loose lids (minumum 500

). You can order smaller amounts from most of the FF vendors, they will just cost you a little more.
If you are willing to deal with cleaning, sterilizing, and cutting coffee filters for the top, then mason jars are the cheapest, most reusable way to go.