There is a dealer in Richwood, Ohio who has a 4200 with about 243 hours, QD loader, hydro, ag tires and is asking $12,900. I found it on the JD site, but only after looking up something else and just browsing what else the dealer had. You could go to the JD site and enter 4200 and maybe find it. For that matter, you could go there and describe the tractor you're looking at to find the going price at dealers. Richwood is about a half hour north northwest of Columbus, so about 2 hours from the Indiana line.
In talking with my Mahindra man who used to work on, then be service manager to, then sell JDs before opening his own business, I think I'd be sure to check into whether all the updates had been done on any '00 series tractor. I think he referred to them as PIPs. Anyways, there were apparently some issues with the turning angles of the front wheels, gearboxes keeping fluids in the right places, stuff like that which only begin to show up around 600 hours or so. He said he had replaced entire front axle assemblies on several.
Maybe someone here can shed more light on the general reliability of that series of tractor and help us both out. Right now, I would shy away from one. Again, this is based on what a guy who used to work on them has told me. He is now a Mahindra dealer and competing with his former employer, so that may influence his opinion and commentary somewhat.