Well su, it depends much on which model 99 you've discovered, and whether it was an early one or mfg. later. To add to the confusion sometimes it's a bit difficult to find out
exactly which model you're actually looking at. Does it have the schnabel forend of just a plain one, checkered or not, walnut or hardwood? Why did they have to make things so confusin'?
I'd never owned a 99 but always wanted to and I've been a .308 fan all my life, so last fall I ran across one on one of the auction sites had the jeweled bolt, case hardened lever, brass rotary magazine, in .308 and I literally paid through the schnouzer because it was 'zactly what I wanted and evidently a couple of other bidders wanted it
almost as bad as I did. Well after I got it I decided I'd paid waaaay to much and I gave myself a good ass kickin'. Then I took it to the range back before deer season and with the first load I put together, with some of the old original Win. silvertips I found on e-bay, it put 3 shots consistently in an inch or under. Well suddenly I hadn't paid too much at all. Of course all my stories haven't ended like this but
even a blind hawg finds an akern onc't in awhile.So while I haven't specifically answered your question, perhaps I have encouraged you to look at it from a different perspective.
If it's in excellent condition and one of the more desirable "collectable" models, expect to pay from $400 - $1,000. BTW, let us know what happens. Good luck. :-)