Can human subjects be paid using a researcher's personal funds?
I've sat on an IRB panel and we've never been concerned about the source of funds for participant gift-cards.

p.s. Note I'm an ethnographic fieldworker and I often buy small gifts for the families and individuals who participate in my projects. It's too much of a pain to pay for these out of my research account (why do you want 15 stuffed bears and keychains?) so I buy them out of pocket.