Sorry I do not know about Paypal. Paypal doesn't allow nicotine products to be transacted so there are few ecig vendors that use Paypal.
Njoy Npro (aka Njoy 2-n-1 at some 7-11's)
Smokestik Hendu
or buy a 4081 to 808 adapter and you can use all of the KR808D-1 prefilled cartos (the most popular 2-piece) - Vapor4Life, SmokelessImage, Bloogplanet, Halocigs G6 have KR808D-1 threaded prefilled cartos - but I doubt any of them use Paypal.
And teach your parents to keep them damp with eliquid. I HIGHLY recommend manual batteries - AZSmokeFree should have some manual RN4081 batteries and I think the manuals may be totally sealed on the threaded end. It's harder to damage or kill manuals with juice leaks, and manuals make it easier to get a good hit