I was buying of season Xenos from Core for $175, dd would use them for a year and then I selling them for about that on eBay or locally. By the time it was over, dd could use a bat for as long as she wanted and it would cost $20. I would jokingly tell my wife it was a $20 Bat Rental Program.
I was able to do that a couple of times...buy a new one on clearance, use it for a while, and then sell it for nearly what I paid. I did train DD early on to hit nothing but softballs with her good bats, and I mean nothing. Not machine balls, not TCBs, cleats, or even the ground. Bat went back in the bag between ABs. It's amazing the wear put on bats simply by banging them on metal cleats or bouncing them around in the dugout.