Well, at the risk of annoying some of my friends, I’d suggest there is very little reason to own a used SR20. I flew one for about 3 months while my 22 was getting R9 installed (long story) and really missed the 22. The performance difference is breathtaking and I really felt the 20 was struggling on hot days with any weight. Seemed more “lethargic” than my Archer. With the 22 you have much more power that mild DA issues (yes look at the chart) and pretty long runways are not an issue. The 20’s have fewer systems to maintain (no AC, no TKS, no power) and burn less fuel but I suspect that the real cost delta is trivial as you get there faster in a 22. Mastering the speed of a 22 takes a little instructor time, but is second nature before you know it. If you plan on renting your plane to a FBO or flight school (usually bad idea BTW) then go with a 20 as qualifications for a rental 22 will keep it on the ground much more.
If you usually fly short distances alone at 4-6000’ and want to rent the plane get a SR20, else I predict you will want to step up sooner than later. The cost of step up is huge compared to the maintenance delta. Most of us fly NA22s in the 8-12k with occasional flights up to 15-17k (ie over mountains or maybe weather with lots of outs). The turbos tend to fly mostly in the mid-high teens. Rough guess on economical cruise speeds would be 135, 165, and 185-200 for SR20, 22, 22 turbo etc. For training or messing around both planes fly identically at 120-130k, just throttle back on the 22 and it becomes a 20 and with similar economy.
There are lots of threads (ie join up!) comparing 20s vs 22s vs turbos etc. You can read for hours and worth the $65 not to mention membership seems to have a big safety advantage.