i have a '91 radian Yx600. Very close to xj's and fz's. YX, XJs are all easy to work on, great bikes.
If the bike doens't need anything done at all to it - maybe. But you are getting at some heavier maintenance items past the 30'000 mark. If you can do your own wrenching - no big deal.
Does it have rust, scratches? Look at exhaust from underneath. Check for rust in tank. Has the fuse box been replaced to more reliable ATC/ATO automotive "flat" fuses?
Is the chain stretched/rusted? Sprockets, are they worn? Tire codes, if tires are old or cracked - they are expensive.
Most common problem leading valvle cover gasket, any traces of oil? When was last carb sync done? Does the calipers need a rebuild? Brake lines are they still factory original - or they have been replaced/upgraded?
Some xjbikes and xjrider are good websites for info on the bike and maintenance xj4ever has a good collection of docs from the first.
If it is was well cared for and in pristine condition - 2500 possible but in my books is high. Although admittedly i don't know the XJ prices. For a radian, that would be too high.