I can't give you any input on the legal side of things, however I commented on a thread about 6 months ago regarding gift card fraud[1] and the assumption that it's a new phenomenon.
With gift cards, especially Starbucks gift cards, it's almost (if not literally) impossible to verify legitimacy. Generally, almost anyone attempting this type of fraud, even at the lower levels will:
- Mask the fact that funds are loaded with credit cards in the transaction log by purchasing gift cards with gift cards.
- Use services[2] which sell residential IP's by location (infected systems) as proxies
Unfortunately for the service your offering, Starbucks has an internal chain-disable feature which deactivates any gift cards "downline" of a fraudulently loaded card, hence it's entirely possible that after conducting a card transfer, even one fraudulent transfer could put the entire balance of your legitimate holding account at jeopardy, and the average Starbucks call center representative will be unable to help you.
Services like Cardpool (also offered in-store at Safeway locations) verify individuals identities prior to cash-in, however even with that the amount of fraud they experience is staggering. To give you an idea, the rate of successful, fraudulent transactions experienced by Cardpool in Safeway stores for 2012 was over 20%, compare to the average chargeback rate on an adult site, which is between 0.5 and 2%
I think you've made a smart move to put your project on hold until you have a better grasp of the entire situation.
[1] https://news.ycombinator.com/item?id=6175294
[2] http://5socks.net/