if you want the bike, then get it if it has no issues.
forks are easy... if you're going to do just one fork, it'll probably cost around $120-150 if you take it off yourself.
if i were you, i would do both forks at the same time... change the fluid, bushings and seals. max it's going to cost you is $300 if you take the forks off yourself, which is pretty easy.
take the wheel and front fender off. unbolt the brake calipers. Might have to take off the front cowl, loosen lower triple, clip ons and upper tripple and the fork slides out. bring it to a dealer and they do the rest. Or change the rest yourself, but you need special tools and other stuff. better leave it to a professional.
I change the fluid in my forks every winter when i strip my bike. you will be surprised how many people never change the fluid in their forks. if we had riding season all around, I would change it minimum twice a year.
anyway, good luck with purchase if you decide to buy it.