I'm sorry, but I personally don't think it has any inherent value undeveloped. There is practically nothing in the way of search volume. The results on Google are confirming that it isn't really a common phrase. For example, the two words appear back-to-back but in separate sentences, surrounding a hyphen/colon, in ways that simply are not "phrases," etc.
I can see how it could be used for something in the way of "credits only" rather than cash. Perhaps that would be something like a credit-only refund center (though I'm not sure how that would work without working with stores), or more feasibly an affiliate network for credit rather than income.
If developed it could have value. Right now, I don't see any. It could possibly go for ~$10 to someone who wants to personally develop it and put it to use.