In my experience, enjoying doing stringing is another factor. I had 3 stringing machines before I settle down with the neos 1000. The last one before neos was also a crank machine. But the clamp is not great and a bit awkward to work when string close to the end of the racket. 6 points mounting get in the way when I doing the cross weaving sometime. All in all, I like to string the racket but not enjoying it with the old czech tension.
Neos 1000 is another story. It is very enjoyable experience. I did my fastest job on neos for 30 minutes but hated it. I like to slow myself down, put on a recorded tennis match, grab a beer and then start my stringing job. I am really looking forward to string a racket now.
I will skip wise. There should be no more extra cost after you get a decent crank machine. Wise can fail and you need to buy it again, which add to the cost.
Regarding selling used machine, you just need to be patient. I sold my czech on CL in about 1 months. There will be no response for weeks but will sell eventually if you live in a place where have a lot of tennis players.