We were buying from wholesalers but found we actually got the best prices from a small locally owned office supply company! The little home town guys provide better service and prices that are as good as the national chains, and often better than the national chains. We get the sales flyers from the chains here, but find the local guy's everyday price to us is usually as low as the national store's sale prices!
I'd check a couple of your hometown office supply stores. And I'd look to set up an account with them for other purchases as well!!!