I went through this a month ago. As far as I know, the prepaid Visa debit cards don't work anymore due to some change in regulations on Aug 1. That's what the Visa folks told me when I called.
I purchased two cards, a $50 and a $100, to order with at Attitude. I did register the cards online also. These cards were marked for international use (there were also domestic use only cards on the rack).
The purchase was declined by Visa. I called the 800 number and was told about the regulation change. They told me that any new cards going to retail will be marked domestic use only, but there may still be international ones out there (no kidding). They would not refund my fees. Of course, I had no trouble using the cards for purchases locally.
I ended up getting a money order and sending it regular mail, but only because I didn't want to use my personal plastic at the time for financial reasons. I used personal plastic for my first purchase and would not hestate to do so again (but then, I have a legal grow).