In my experience, a 3 piece 60's slingerland set (be it 12/16/22, 13/16/22, or 13/16/20) is generally worth:
-In the $500 range in playeable but cosmetically worn condition, perhaps with some cosmetic drill holes or aftermarket tom brackets/spurs. Kits in this rage, I think, are generally worth a $1000 total investment if you need to completely disassemble them, clean up the shells/edges/hardware, replace missing components, fill holes from previous mounts, and install new heads. I often see kitso n eBay that fit this description.
-$600-$800 in nice, reasonably collectable with no extra holes, other brand hardware, or shell damage but with scuffs, wrap crack, bits of rust, dings on the hoops, etc. Kits in this range should generally be ready to play with perhaps the addition of new heads and a good cleaning. Most of the Slingerland kits I see on Craigslist fall into this range.
-$800-? in collector's grade, minty condition with little to no wear on the wrap and bright nickel or chrome hardware with all original T rods and claws, hoops, etc. At our drum shop, there was a truly mint Chicago badge Slingerland 4 piece 13/16/22 and a 14x5" RK snare all in BDP. It went for $1500 and needed nothing but a pair of sticks.