'Most any Savage Model 99 in working order that isn't all beat up is worth at least $300. Unless you're buying it as a "collector", screw holes in the receiver to mount a 'scope are perfectly acceptable as long as they were properly done and functional.
Items such as a ruined bore, a consideraby shortened barrel or a very shortened butt-stock would keep me from buying the rifle at ANY price, but short of those kinds of disqualifications, a Model 99 would be considered a "good buy" at $300.
However, I'd need a LOT more information to put an actual value on such a rifle. Such answers as what is the serial number including letters in front of the serial number (if any), what is the condition of the rifle in general, is it in 95% condition, 90%... 80%... 70%??? What condition is the bluing in? What condition is the bore in? What condition is the wood in? What caliber is the rifle in?
As you can see, there's a lot of things which need to be considered.
Comparatively, on a scale of 1 to 10 with "10" being the best and all three rifles in the same condiion, the Model 99 is a "10", a Model 336 Marlin is a "7" and a Model 94 Winchester is a "5". Hopefully, this might give you some idea of the Model 99's value relative to rifles with which you are more familiar.
Jus' my 2¢...

Strength & Honor...
Ron T.