So, you're saying if you buy a Visa gift card from walmart, the'll accept it? If they do then i'll be so fucking happy.
If I remember correctly, when I tried to use a pre-paid credit card from wal-mart, I had to activate it first to be able to load it with money, and to do so I had to enter my name, billing address etc etc. I think that's where the problem might be - if you enter different info for the card, and then go to attitude or other such sites, and enter a different address, they might not accept it. I ended up using my own credit card, and had the seeds sent to my own house. Never had any issues with anything.
And I wouldn't try gift cards from wal-mart, most of them can only be used in the US.