Another site I frequent uses www.clickbank.com as their primary source for subscription purchasing. I know Jot's problem with Kagi is they were geared more towards single software purchases (which would send a key), but clickbank specializes in exactly what this site needs: a safe QUICK easy to use pay source that doesn't require any saved information (like bank accounts etc) at all. If he's interested there is an indepth guide for future clickbank vendors on how to set it up:
www.clickbankguide.com

Please please look into it.