I have yet to be impressed by offerings of recent (3-4 year old) skis at a ski swap. Way too much of what I find in the way of recent equipment is BEAT ex-beginner rental equipment, or 2-3 year old used skis with price tags higher than what the same ski is selling for in clearance stock. I don't know who thinks their 3-4 year old Gotamas with probably 150 ski days are worth $500-$600 (or any other similar "deal."
I can't imagine stuff like this sells at those prices, but yet every year, this is what I see equipment priced at. Its like people take the full MSRP of their stuff (rather than the much lower price they actually paid), then subtracts like $50 a year.
I think TGR's ski pricing guide (found in their gear swap section) is much more based in reality- Used stuff is worth 50% of what it currently sells for new or new old stock, minus 10% for every time its been drilled.
I've been to a lot of ski swaps, and so far, I've walked out with a couple sets of poles and a $20 pair of rock skis.
Anyways, back to the OP. I've had good luck inquiring with the on-mountain rental shop, and any of the other larger rental shops in the area, as to when they sell their demo equipment. The high-end demo equipment generally sees less use, and gentler use, than the general rental slop. They also tend to turn around the demo equipment faster than the beginner equipment, because its hard to charge a premium for 5 year old ski technology.
I've had very good luck at getting very good deals on gently used demos, and have bought about 5 pairs of skis this way. My wife scored a set of current-year old K2 Missbehaveds and saloman Z12 demos for $350 in May following the season- the skis looked like they had about 5 days on snow without even any topsheet scrapes. I've scored many pairs of top-end 1-2 year old skis for $200-$350. Just ask them how they go about selling their retiring demos, and show up the day they do.
Along the same lines, look up when your ski hill does a demo day, demo the equipment, find the skis that you most like skiing, and ask the rep how to contact them about buying one of the demos at the end of the year. Manufacturer demo stuff gets sold every single year (can't demo a ski with last year's topsheet), and you also know the ski has spent its life being tuned to absolute perfection while generally getting pretty light duty.