currently, the auctions are the best solution. they don't allow items to go for less than they would eventually sell for (or at least auctions shouldn't, because of the possibility of the aforementioned middleman's profit).
My idea is to keep a separate "average price over net worth" index for base or store-spawned items only. In a few months (or however long it takes for at least two or three of each rare to have spawned) With this number, you could then bring rares out of auctions and back into the store - bringing back "camping" - but the price would be high enough to discourage, if not eliminate completely, camping as it was until a short while ago. OR erase the current values and start everything over - the point is that because things usually sell for [N] base amount + [X]% of NW, the auctions prices for near base and for upgraded items should not be mixed in this case. what the store is selling for should be the market value.
The main problem is setting the market value accurately.
I'm sure that there is an easily-implementable way to keep track of how long things spent sitting in the store + how many people visited the store while it was there.
I think that while this is not as accurate a measure as auctions by a LONG way, it does reflect the demand for items. If you saw a near base elb in the store for 10mil, would you buy it? how about 8? 6? 4? ...1? somwhere in there is the right price.
I think that a sort of reverse-auction could take place with the rares in the store. after getting a ballpark estimate of the market value of a given rare with the separate A.P.Over NW numbers, when they begin spawning in the store again it would be somewhere to start from. From then on, whenver a rare is bought, the next time one of that type spawns the base price goes up 10%. each time they "die" from the store, the price goes down 5%. If 48hrs proves too much, it can be tweaked.
...or you could just set some arbitrary base values for things through the polls or something.