The danger of Paypal friends & family is, I think, that there's no recourse if they just keep the money and don't send you anything whereas if it's "normal" Paypal where they take a cut then you can apply for a refund if you're scammed. Vouchers sounds like a way of avoiding tax at best.
I find CEX good for 2nd hand technology. Their grading of condition errs on the side of caution and I've bought things off them before that they've rated as having clear signs of use and I've struggled to see where. Pretty sure everything comes with a warranty too. The website shows where things...