Pay cash. You can get a refurb at $600. It's totally worth it.
Speaking side-sleeping, I have sewn a sock with a tennis ball to the back of my sleeping tshirt. It worked well, but it's hard to wash. So I bought this contraption: https://www.amazon.com/stream/ref=nav_upnav_mobile_T2_Detail...
Side-sleeping is a big deal, but it's even better with a neck pillow.