I would like to get a mod21; however, since I know very little about the guns and I see prices that range from 4k+ to 8k+. What is a proper price and what should I look for?

See if you can find a copy of the book Winchester's Finest- THE MODEL 21 by Ned Schwing. 357 pages of everything you want to know about the 21. If you want a upland gun, the 16 ga. is the way to go. The 20 ga is not bad either. The 12ga can be a different story.
You can PM if any more questions.

Byran
My 16 ga weighs under 7 lbs. with either barrel.

Highly recommend that you buy a Galazan version as they are better in every sense than the originals. Resale is good as well.

Depends on what you are wanting to do with it, but, should you just have to get an original 21, my experience is that the Pre-war guns are hof a better grade. I've owned over 50 of these things over the years and am way-deep in the high grade models at this time - love'em but they are not the guns everybody thinks they are...

PM me if you want to know more...

..JW