All things considered (cost, engine performance, suspension, handling) the YZ250 is one of the best bikes to have. It can do it all, and works well stock. They are fun to ride, and unlike a 450, I can hit WFO and hold it there for a second or two. I'm no RC!
I got a new 2016 for $7,500, paid it off in about a year and a half, and kept it mostly stock. With a Boyesen RAD Valve and Air Wing, front rotor, and 9oz. FTW, it hauls ass and works great. I can go faster on a 450, but am having fun and I believe going at a safer speed on the YZ. At my age (35) I just want to be safe and have fun. Keeping the kids at bay is a nice thrill, but I'm not going to wad myself to stroke my ego.
Doug Dubach (YZ Master) said on a podcast that good used YZ250s are hard to find, so I imagine ones in good shape hold a good price point. I bought new to keep my credit current.
It is interesting that McGrath wants two-strokes to return, RC did a cool video on an RM, and Reed got a 2016 YZ to work on as a project bike.
"Thank God my father wasn't rich."
-Hurricane
"You wouldn't take clay to Southwick, so why take sand to Red Bud?"
-DV
"I ride a two-stroke because I am Weigandt-level cheap"
-Me