The best gauge of what your average Joe is willing to pay is to look at ebay "sold" prices for actual auctions. There's little logic in ebay "sold" BIN prices and none whatsoever in BIN asking prices. Occasionally a seller will list something at an extremely low BIN price, well under recent sold prices, because they don't know what they have, and it'll be snapped up quickly (and very possibly flipped). Sometimes an auction item will go for a very low price because demand is temporarily low (like the day after Christmas, or maybe quite a few of that particular lens have sold recently and there are few or no buyers at that moment, or because the seller has very low or poor feedback.
As far as what's the "best" lens, there's no way to say. One lens might be marginally sharper than another when looking at resolution charts but it might have uglier out-of-focus rendition. Or maybe the color rendition won't match other lenses you've already got. Some people don't like the newer multicoated plasmats (most of the lenses you mentioned other than the Pentax follow the basic plasmat design) because they're too sharp - instead, they might prefer a single-coated older Fujinon like the W S with inside lettering, or even something older like a Dagor. Maybe you've standardized on 58mm filters - in this case the 180mm Apo-Sironar-S might not be "better" for you because it takes 67mm filters.
Trying to find the "best" lens is a silly exercise, IMO. Rather than stressing over how many angels can dance on the head of a pin, buy a lens in good condition and use it for a while doing your type of photography. If you like the results, keep it. If not, get another, compare the two, keep the one you prefer, and sell the other. You can do this exercise as long as your patience and wallet hold out, but remember that even the most expensive lens in the world isn't going to make you a better photographer.