The reality check on Ebay on your searches is go to 'advanced' and check completed / sold listings.
That will tell you what things actually sold for, or didn't (completed, no takers) over a time period.
If you're a smart seller, you go there first, and set your 'buy it now' price accordingly. The only time you'll see an auction anymore is when somebody has something odd or clueless enough there's just nothing like it and nobody knows. Good example I was watching was a semi-completed GHQ Pewter L1 boiler and tender shell, no mech, painted, no trailing truck casting.... geez, what's that worth?
Seller listed it for a buck in auction mode and it got like 26 bids and went up, way up, to $89. No, I didn't get it, but yeah, that's the market.
If you're listing an old Roco GP9 for $90 for buy it now, that's will be a swift kick in reality, if people know what they are looking at. You might find a sucker to take it not fully knowing what it is. The 'N Scale High Speed' locomotives that were readers digest specials, dummy units, and are really ugly copies of Bachmann GP40 units are everywhere looking as traps for the unwary.
About the only real 'deals' out there are the Clueless listings, where people don't know what they have and list it cheap, often estate sales. 'N scale steam engine $9.99' and you look at it and it's a Hallmark brass Northern. Holy crap....shhhh. The other 'great deals' are damaged and dented when you know it's fixable. I got a 1968 Jamco 4-6-2 that had met a basement floor with a dented pilot and whacked handrails for $50. It was heavy rebuild meat anyway. So yeah, have fun looking for 'parts only', 'damaged', and 'does not run'.
But honestly, the 'buy it nows' are great because most times your shipping is less on a couple small items than if you ordered it online. Micro Scale, for instance, has a minimum order amount direct and hoses you on shipping, but almost any decal ever made is still on Ebay for minimal shipping and first class mail. And there are a lot of good sellers out there, keeping their brick and mortar operations alive as well.