Hmmm... i did not see many used hp boxes with replaced posts.
Well - i am using used gear from hp. Because i know, it is not made by compaq-hp and has a higher quality than many of the brand-new today's devices, especially when comparing the price.
On old HP-Boxes (and the ones from other manufacturers) i see dents and cracks on the knobs very often. Dents are the result of bumping something onto the device. Well, it's quite normal that something that sticks out of the device is more suspectible to be broken.
There are some - in detail visible - advantages of the hp-posts compared to cheap ones (this does not mean that there are no other good ones on the market, but these are not cheap too). Longer lasting materials, terminal plates even on the screw-handle and so on. On old devices with cheap posts you will get contact problems very often.