try the simple visa gift card in the yellow package available at most large stores.  Avoid the sub brand "vanilla" or other decorative packaged cards as there is something different with these and they don't work.  I have always used "happy shopping" as the name because that's what it says on the card.  Having said that, I haven't tried this in a couple months so maybe thins have changed.  

Also, most cc merchant services will draw an additional 15% or so over what is requested to verify room on the card for gratuity etc so trying to use a $50 cc for a $50 purchase will most likely be declined.  Next time you use your regular cc at a restaurant, immediatly go online and look at the charge posted and you'll be surprised. You very well may see the transaction that you endorsed at $80 posted at $92-97 until the merchant who took your card actually closes his system out at the end of the business day/night.  Then your charge reverts back to the actual amount endorsed.

I usually buy the $100 card and use $50 for membership, then stick the rest in my gas tank or other point-of-sale transaction that will not be subject to the merchant account "buffer" amount.  My .02, good luck