I realize im rambling here, but im hoping my thoughts may spark conversation and more ideas. : )
instead of a magnetic stripe card, what about using a barcode. You could print custom barcodes on the back of the gift card/business card with the number. I hear that some cells can scan a barcode and bring up a website or certain content. So in theory if you have one of these phones, it could even access a database of gift card values. These values could even be stored online if the cell has internet access. These barcodes are a square, but thats all I really know about them.
I wonder how many numbers I should use on these gift cards, since its a small business, I dont expect to sell millions of these, and the more numbers there are, the mor eyou have to type in or write down. im thinking 4 or 5 numbers, but will that seem "small business" to the customer?
To save even more money, im thinking of getting single sided cards, and use a rubber stamp to print the numbers on the back of each card. But then that could be smudged off and/or new numbers put on with the same device. If its printed on the card or with a font thats hard to recreate it should be a bit more secure.
I priced moo.com and 200 cards is like $70 plus shipping. Theres a current deal for 250 or 500 cards for $10 but its single sided. Thats why I was thinking about using the stamp. Its to bad my printer cant print some something this small. It would make the custom side easier and cheaper.