Well, old computer stuff varies in price a lot. It depends upon how knowledgable the buyer is, how knowledgable the seller is, and how long either party is willing to wait. I know that I've picked up $400 or $500 "worth" of vintage hardware for $75. I have also found supposedly rare stuff for a song in thrifts. The thing is, you have to be willing to wait, and if you are not going to wait or you don't know where to look you're not going to get a good price. (The inverse goes for the seller.)

Software is also something that you have to be careful about when assessing it's value. To some people, software is absolutely worthless because they can download it from some random hotline server. Downloads aren't rare. They simply exist or they don't exist. If they exist, they have no value because they are infinitely reproducable. If they don't exist, they have no value because you cannot get it. That sort of thing taints the perception of the value of boxed copies in the eyes of some people.

Yet if you want a boxed copy, you have a problem. There is scarcity, and really old software is really scarce. Boxed software is even more scarce because people get rid of packaging and leaflets. Shrinkwrapped software is likely worse, simply because you are depending upon finding an unsold copy OR a business who bought multiple copies for multiple licenses (and that was less common in the past). So yeah, some of it has value.