I may be out there but bear with me.
4310 is going to be a 10 year old or so tractor any way you cut it.
130 hours is nothing though, almost makes you wonder where in the heck was it?
To go buy it today the model would be the 3320, with loader and canopy, ehydro and taking off what you should be getting off from the dealer you are in 24,000 territory +/- new. (no taxes in my figure here).
So, at 10 years old and barely used go over it really good, I mean real good. I would be more worried about dry rotted hoses / tires / any rubber or plastic parts. Old fluids, etc. If it all checks out and you can get the dealer down a little as well as maybe a full servicing (engine and hydro, all filters changed) it sounds like a very fair deal to me. But again, only if everything is in great shape.