That's not true. Sometimes there's not a lot of demand and you pay much less than average market price.

If something is priced super low then someone might step in to arbitrage, but even with perfect knowledge in a perfectly efficient market, an arbitrager will only be willing to pay the true value minus the cost of relisting, the cost of reshipping, the cost of their time, the cost of tying up their money, and the cost of the risk it won't resell. If you beat that by fifty cents you'll get a great deal on the item.

This either limits the number of bidders though worse discoverability or just less desirability and lower prices.

I don't find auctions exciting or compelling, so I doubt I'd get overly excited about bidding. I'd just set a max bid (probably about half what I would expect to pay with "buy it now", to compensate for the extra delays and hassle involved with auctions) and call it good. If I'm outbid, I'd just do the straight purchase like I would have anyway.

The reason that unnoticed auctions might be worth me looking at is to expand the pool of possible sellers to buy from. Although if my bid makes the auction suddenly attract the attention of automated bidders/snipers, then there's no point to it for me. This might be a nonstarter.

I'll probably give it a try and see how it goes, though.