Im very very interested in this current topic. I use Starbucks frequently and have so far held off from buying them because I can't rationalise why Starbucks would allow people to consume with such heavy discounts... are these cards stolen?
Be careful buying **ANYTHING** from places like this! It's like going to the casino and gambling. You can't trust ANYONE. Seriously, people are buying and selling "trusted" user accounts on this forum! You don't even know if these "trusted" people are really the people they say they are and just aren't scammers who bought the account for a few bucks. Look at all the ads for BITCOINTALK.ORG accounts for sale or wanted. Why do you think people buy "trusted" accounts?
There is NO WAY Starbucks would ever sell such cards at such a discount. There are 2 possibilities. #1) They are purchased on stolen credit cards, #2) Someone has hacked into the Starbucks database that generates card numbers an PINS.
That being said, I have purchased well over $1000 worth of cards over the last year for PERSONAL USE (not to resell) at an AVERAGE value of ~60%
off of face value between eBay and here and have so far had ONE card shut down. Fortunately that was from eBay where eBay or PayPal will (did) make good. On here, you have to be willing to take a risk but DO NOT BELIEVE FOR ONE SECOND any seller who says they "guarantee" anything. Their "guarantee" is worth as much a the paper it is printed on. Right, it's not printed anywhere!
If you do buy cards don't merge them with your existing cards. Keep them all separate otherwise if one is bad and it's mixed with good ones the ENTIRE balance (good and bad) is shut down. If you keep them separate worse case you lose the one card.
Bottom line is, it's like the old wild west .... you just have to be willing (or not) to take a gamble.