As Muppity said you can't buy PUL from SL. From most reports if you ask them they have no idea what it is and have told people to get ripstop nylon which doesn't work.

They sell metal snaps that you bash on with a hammer. They do work alright but depending on how many you are going to eventually need, will cost more in the long run than buying a snap press. I'm also not sure how they will stand up to constant use and if they will rust eventually.