Shipping gets out of control quickly on tray inserts and pots. Try to get as local as you can.
If you can open an account with BWI that would be great. They are a reliable wholesale company and actually have route trucks in your area. Minimum order amount might make it not so practical. If you can't come up with the minimum then perhaps others in your area could form a co-op to buy from them.
http://www.bwicompanies.com/default.aspx
Another one that is sort of close is
http://www.growersupply.com/
I got my 3201 sheet pots from them last year and they were quick, and cost effective. Their prices are always good and the shipping is decent because they are so close to me. I am very pleased with B & T Grower Supply and I will use them again this year for the bulk of my supplies.
I have also ordered from Green House Megastore as Ted suggests and they are very good too.
Best of luck.
--Steve