Try calling some glass dealers in your area. Look in the Yellow pages under such titles as Glass, plate or storefront. Also possibly windshield replacement. The windshield only guys wont be able to help, but the ones who deal in storefront glass as well will. One inch is very expensive. If you don't have any luck, let me know. I may could help out.
Do you need a whole sheet (usually 4 x 8) or do you know what sizes you will need?
I buy direct from glass mfrs and may could get you a deal on some, but shipping from SC on a whole sheet would have to go truck and would be expensive.