Some places do not have them anymore and only have the GBA cards, so be sure
to email the place you're planning to buy from and ask. They probably won't
make them anymore if people only want to buy the GBA cards, which do not
work for original gameboy or gameboy color games.
I bought one from cd64.com about 2 weeks ago. They charged high shipping
costs to make up for their list prices being a little less than the other
places, but overall the cost was about the same. I got it about a week
after I ordered it and didn't have any problems with US customs. (No taxes)
The label on the cards says "Mr Flash 64M".
It works fine, but I only tried about 5 games so far.