Many office supply retailers offer special discounts to loyal shoppers. My local office supply store is part of national chain, but the store personnel greet me by name. I have been quite impressed with the rebates, discounts, and rewards programs offered to me in exchange for my loyalty. In fact, last week my purchase equaled $90 in value (non-sale price), but I only paid $15 due to taking advantages of specials for repeat customers.
You may wish to check with your office supply vendors to determine what types of programs and discounts they offer to repeat customers.