Originally Posted by Klemhuzzah

2 things - a lot of gas stations don't sell the $500 cards. I think (not sure, and YMMV) but BP doesn't. And if you have to settle for a $200 card, then the $6.95 fee wipes out most of the profit even at 5%

Second, Walmart doesn't like Vanilla cards, though again YMMV. With Vanilla, I think they only allow loads under $50, ie $49.99 max. I'm surprised your $50 card worked. If you found a unicorn, you'll probably want to keep it to yourself.

Good luck!