I agree with Superior Shipping Supplies, a good selection of many different sizes, punched and unpunched.
http://superiorshippingsupplies.com/...mart&Itemid=53
I actually wash my deli cups and use them many times before throwing them out though I gotta admit that some days I sit there staring at a small mountain of dirty deli cups with a look of dispair before deciding to chuck out the whole mess and just order some more. It's nice to have the option.