Test: Are you consistently buying the largest size offered by your distributor?
If you’re buying a dozen at a time, a large distributor with a big catalog is the right source. If you’re buying full cases, that’s a sign you may need to find the next level of supplier.
If you've emailed your supplier asking for bulk pricing beyond what's listed on the website, that's a nearly sure sign you should re-source to a new and bigger supplier. Be sure the supplier offers a significant discount if you're purchasing in large quantities.