Can I use primer for multiple purposes?
I highly doubt a paint store sells what you are looking for.  When you join two pieces of PVC, you aren't joining them together, but welding them together.  PVC Cleaner (AKA Primer) cleans all dirt, and oils off the parts and soften them a bit, so they weld together properly and the glue can penetrate the PVC deeper.  The glue then works on a molecular level I think to "melt" the pieces together to make one piece of PVC.  You need to go to a hardware store to get the correct product.  You can get PVC Cleaner/Primer and Glue separate, or you can get a Cleaner/Glue product in one can.