My experiences on this:
I've bought skis online, in stores and at ski swaps. No bad purchase experiences. BUT, that's because:
- I know ski gear & what I want specifically.
- I don't mind buying gear that is "new" (unused) but older models. I rarely buy used gear. If I do, I almost always buy from somebody I know personally.
- I only buy from stores/sites/sellers with really good reputations. Period. If they don't have a good established 'rep, I don't buy from them.
- I never buy from private parties on Craigslist or Ebay. Too sketchy for my tastes.
- I avoid buying from a source that just recently became a vendor/seller. For example, on Amazon or Ebay storefronts, you can see info on the seller of a product. Sometimes you'll see they became a seller just a few days ago and haven't any feedback yet. Way too sketchy for me, regardless of how sweet their price is.
- I never buy from a source that doesn't have a return policy that I can verify is a good one.
Some of the above usually don't apply if you're buying at a ski swap. Typically, 'swap gear is sold "AS IS" - no returns. So, you really need to know your gear when buying at a ski swap.
I'm very patient & very selective on my gear purchases. I'm willing to wait for many months (even a year or three) for the gear I want to be on a good sale. If the gear I want doesn't ever show up at the prices I'm looking for, then that's OK - if I really need the gear at that point then I'll buy from a local shop.
I've been pretty lucky for a while. All my skis purchased the last few years cost me in the range of $250-350 (US). Typical shop prices for those skis would range around $700-1200. Best deal I got was $265 for a pair of (discontinued) unused "new" Kastle LX92s (shops sold them for $900-1200).
Many US western ski resorts had pretty marginal ski seasons from 2012-2015. Ski shops had a tough time and, I believe, there's still a lot of excess inventory - particularly wider powder-centric skis.
Lastly, if you are unsure of a seller/source that you're thinking of buying from then run it by the folks here. And, if it's a really sweet deal, be sure to share that info with us. ;^)