Don't sell your Power! Pawn them instead.
I was laid off a few months ago, and money was REALLY tight.

I really didn't want to part with my Power, but the mortgage was due... I must have called about 15 pawn shops, and the usual response was "Power What!? A card game!? Nah, we don't loan on those..." Finally, I spoke to one guy who not only heard of Magic, but used to play back in the day. He looked up the current cost of Power on eBay, and promptly loaned me $1000 on the spot.
Well, I'm working again, and my buddy Jeff spotted me a good portion of the buy back price to get my Power back. In the past three months, these cards have gone up quite a bit, and I'm thrilled to have them back.
So some food for thought, if you're in a bind, consider pawning rather than selling.
