I'd say about $600 if the kit is in what barjack describes as reasonably collectible shape (no extra holes, all the correct hardware, minimal scuffs and rusting). I really wouldn't ask more than that for it, especially if you don't have the specific snare that went with the kit. I know barjack gives a range of $600-$800, but I think $800 is too high (and trust me, there are people who will think that $600 is too high).
$800 is certainly not too high if traded on the national/international market to the right audience and with a kit in the right condition. In my market here in the Pacific Northwest, it's rare to see a reasonably nice Slingerland kit sell for LESS than $800. Those below that pricepoint are generally in need of complete restoration. Heck, a 60's Ludwig or Slingerland kick drum with all its hardware and a decent Superkick batter will sell for $300 alone, a floor tom for $200.
I only have access to the Canadian eBay here at work, but even searching the limited "Completed Listings" section, I'd say that pretty much any good condition tom/floor tom/kick Slingerland set from the 60's and 70's on the site gets at least $600 worth of bids, far more if you factor in what the buyer is shelling out for shipping. The WMP 3 piece below sold for over a grand.
