$400 Value of used Whites XLT and Lesche???

If there truly is something wrong with it, and you send it to sweet home, I'm sure you'd end up right around your original $400 price after the repair bill from White's. If there isn't truly anything wrong with it, and maybe he, say, has the gain/AC sens set too high, making it chattery, or the coil connection is loose, or the coil is out of tune, then you'd be getting a deal if he takes $300 for it.
IMHO, it's a win win.--what accessories is he giving with it?