The stans hubs are easy to swap between QR and through axle, you just pop the end caps off and pop on the other style.

Rockshox Reba can still be found new with a 1 1/8th steerer and would be an upgrade. If it is worth spending the $500 compared to a recon I can't say. There aren't a lot of good 1 1/8th steerer forks out there anymore.

Used is a good option if you comfortable with the idea of rebuilding/changing the oil in a fork yourself. Just stick to newer stuff and avoid older worn out stuff. 1 1/8th steerer forks aren't in demand so they aren't worth much on the used market. ebay, pinkbike, and local facebook groups are good places too look.