I couldn't get a prescription pump at first so I turned to Amazon. At first I got one with a squeezy ball type pump which didn't last long. You can buy all the bits, tube, actual pump unit and seals separately. Then I found a handle/trigger type pump seperately which I have had for over a year and it works perfectly. I also bought seperatly seals which I had to trim, they are cheap so you can get a selection. Also a longer tube to join the pump to the penis tube. The cheap ones are not so easy for transferring the ring from pump to penis without losing the vacuum, but once you get the hang of it it's ok. One advantage of the cheap one I got is it is light and will hang on while standing in the shower etc. and I can stand at the basin and hang the pump part on the cupboard door to support while shaving. The seal I got separately is actually more comfortable than the prescription one. All in all if I could only have one now it would be the light weight cheapy but with the rings from the prescription one. You can by the proper rings alone from Somarect.
Performance wise they do exactly the same job.
My cheapy doesn't have a pressure relief button, so just pull the connecting tube off when I need to release.
Good luck to you both
Cheers
Bill