The price of these fluctuates depending on server activity, namely how fed up are those farming for them and how many PDs have they managed to hide away/rmt while doing so.
Barring the "event team" doing something woefully retarded you can currently expect 300+ for most of them but demand will be your biggest killer. SJS is regarded as the most 'useful' uber, with PW 2nd and HP 3rd and is reflected in their historic prices of ~400 ~325 and 250ish respectively.
HP is the hardest to hunt, but has the lowest demand by far. They tend to sit on tradelists indefinitely or get sold well below the price of other ubers. Historically I believe the most expensive uber was PoM bought though a platbadge, but with all the drops recently that looks like it was a pretty poor decision.
In either case, people will hound you with lowballs for these things when you sell, but unless your in a hurry 350 is easily doable.
