Tigercat 630

I bought a Tigercat 630 a couple of weeks ago. It's a 1997 model with over 7,000 hours on it. It's been sitting since shortly after 2007 (that's the date on the old batteries). This is a "it was working when it was parked there" purchase. We checked all the fluids and brought them to safe levels. The only thing low was the hydraulic oil. I made some 14' long 4/0 jumper cables and after turning the engine over a little it fired right up. The alternator was stuck so we freed it up and cranked it back up. It moves smooth and the big claw in the back works. This thing is a beast with lots of life left in it. The A/C even worked! I've never messed with a Tigercat before but I can tell this this thing is well designed and made to last. How much might one of these be worth fully functional? It's 24 years old and would probably make a great backup machine.