An attempt at answering the original posters question; it really also depends on the particula Pentax model.
I've seen some Pentax LX models that hold onto their value quite well. Even a LX's that was in original box and never used going for considerably more than it ever retailed for. Also saw a rather nice LX type of outfit (also never used); that included different finder, screens, and more hardware than could ever fit into one bag - all sold for over 10k
Also to compare some of the Sony and Pentax line in general...
Generally most Pentax hardware is made with a better build quality than most existing Sony lines. But there are exceptions... Some of the Sony models such as the V1 or the R1 have very impressive build quality.
Originally posted by Origineelreclamebord Aren't people deterred by the fact it's a small brand
The truly rare cameras such as Hasselblad, Leica and others also do not sell well at all. As a matter of fact there are some Leica's that are real sales flops. But they are also still quite collectable. Case in point... The Leica MP's are quite impressive; also the future Leica Monochrom (without the E on the end) will also be quite collectable.