That is the beauty of the D600,. and Nikon,,, it opens up the whole 50 year catalog of lens to choose from.
Actually, due to the sheer number of Nikor cameras DSLRs sold that can use old lens, Used prices have climbed and climbed. More and more people have learned the value of their lens. So, sometimes you have to hunt to find the deals.
If you use EBAY,, look at the closed listings to determine what the average going price is.
Also,,, get those ED lens before Nikon phases them out, typically way less then the current G lens, for high quality build, and
great optics,, for example... Nikkor 60 mm ED.. so so nice. or say a 50 mm 1.4 non G... Your camera has the drive for auto focus,
so,, no issue for you.
Also, you can even use NonAI lens, but you have to sometimes have it converted which is a simple as grinding some metal off (I pay 30 dollars at a local shop for this), but, while the nonAI build and focus is often fantastic, often they are just a bit (and I am talking small amont) less sharp then the later AI versions, but you got to remember, non AI lens are like 50-60 years old, which is simply amazing! I have a 135 in which the build quality just blows the mind, its more a work of art actually.
Don't bet me wrong, G lens are fine, I am slowly adding those too, just more money,, often more bulkier, and well just incremental optically in some cases.