All depends on how hard the sled has been ridden through the years and what has been done to it to keep it maintained...
Exhaust might be the biggest problem, try plugging the exhaust while the motor is running, if it stalls right away you are good to go for now,
The stock hand warmers pretty much are useless unless the previous owners have put on the yamaheaters which are awesome, a must have if you end up buying it,
Check to see if there is a rear cooler behind the snow flap or just the pipe going across, that would be a nice upgrade,
Check fromt arms bushings for any play, a lot of us on Ty have put on bronze oilite much better than the stock bushings,
I don't think there was much problems with the suspension breaking, only thing is it was as hard as you can get it lol,
Most of the stuff listed could already be done since its a used sled,
And of course take a look to see how the normal wear and tear parts are, rear wheels, track, sliders, steering bushing etc, prices add up pretty fast if you are on a certain budget ,
I'm sure more will add what I missed,
Good luck...