The spcific glue for spaflex is difficult to locate, some Spa service type companies carry it but were out of it when I wanted to do my basement plumbing. I called the company that makes it and they said to use the blue can stuff from Home Depot, "Rain-R-Shine". They also said not to use primer on the spaflex itself so when I'm gluing it to the PVC pieces I put primer on the hard PVC, then glue, and then just glue on the spaflex.
I read all the spec sheets on the various glues and the primer and most of them are the same ingredients just the mix is different and that includes the purple primer.