Help with PVC Dinghy repair.

I have a Bombard Tropix inflatable that has a patch that is leaking. I
am going to attempt to remove the patch, and put on a new one. This
patch has been leaking since I bought the dinghy last year. I have used
seam sealer on it, with spotty results, and have attempted to peal some
of the patch batch to re-glue, with no success.

What is the best method to repair this? I will use a heat gun to remove
the old patch, and cut a new patch out of some PVC material that I got
with the dinghy. I have some PolyMarine glue, but I read that the
two-part glues are better. I also was told by a friend who does ceramic
tile, that the PVC shower pan glue should work also.

Has anyone use this shower pan glue for patching a PVC dinghy? It is
made by either Pasco or Oatey. It is considerably less expensive than
either the two-part Stabond or the PolyMarine adhesive.

I would like a patch that would hold. The difference in price between
the shower pan glue and the marine PVC glue is considerable (shower pan
PVC adhesive 6.99, PolyMarine two-part at West Marine 39.99). Is there
that much of a difference between the two, or is it the standard
"Anything with Marine in the name is going to be triple the cost."

Any help would be greatly appreciated.

Bill