I use 16oz del paks for adults (inside of 4" PVC couplers) and 8oz del paks for juvis ... they come 500 cups per case.

I used to order from www.foodservicedirect.com until I found a local paper supply house that delivers for free and is about 1/2 the price. They do have a pretty large min order, but it works out to about what we go through in a month.

Hope this helps.

-adam