I hate Best Buy but I'm going to post this anyway.
I just picked up an Eye-Fi Mobile X2 8GB card for $43.99 at a Best Buy store. They have it listed online here for $87.99 but when I called to set it aside for pick up she said it's on sale for $43.99. Sure enough, that's what I paid for it.
You probably can't get that deal online but if you're in the market for one and have a Best Buy store nearby, it's worth calling to see.