Have you measured your posts by chance? If they are a whole number, maybe even 1.5'', 2.5'', 3.5'' etc you should be able to find PVC pipes you could cut down to a better size. They don't have to be thinner on one side like the posts that come with the shelving unit, there should be a lip inside that will hold the PVC. Even if it doesn't have the lip you could put a screw through the PVC to hold the shelf in place and cut the PVC to the height of your shelving unit. The posts that came with this shelving unit are a typical PVC size.