One thing to be careful about now that eBay is moving away from PayPal.
I placed a $500 dollar order. One seller is now on eBay payments which does not offer the 6 month interest free. I was however, given the option to split payment. It took me to paypal 1st, showed $20 off and said I would then be taken to eBay to complete payment processing.
When I got to the 2nd part of payment, the 10% was not there. I clicked on confirm and pay thinking it might show up there and give me the option to first "confirm". Nope, it immediately processed the remaining $300 without applying the coupon.
I called eBay. They said, "sorry, it only applies to one order". I pointed out that this was one order with a split payment. Basically, they said "Too bad", they treat it as two orders.