It is incredibly easy to transfer money between gift cards with Starbucks and this is why I believe many of the gift card sites do not want to buy the cards. Once they issue a check, you could theoretically do a balance transfer and the site would be stuck with a $0 card.
I still have a couple hundred dollars of Starbucks left from a peak of $1200. My average cost was about 76% and I was selling it anywhere from 78% to 81% either from a straight percent or after TopCashBack and eBay Bucks. Plastic Jungle was by far the easiest to sell the Starbucks. Cardpool and ABC Gift Cards were the most painful.
I had left the gift card name in one of the posts and Al, a reader, pointed it out and I edited the name out. He is correct that they can be found on eBay quite easily and cheap too. I would not mind buying more Starbucks cards for personal use. For gift card churning, I will no longer do. It caused me to be illiquid while churning as I had a fixed budget.