That puts it squarely at the bottom of the depreciation cycle and just about to come up in value after a while. Like what
barythrin was talking about. At the moment, the values is about nothing, but it is sure to start going up, and is sure to be somewhat collectible in 5 or 10 years. I got a couple of these a little while back which were slated for the dump. I use them to run DOS, but old UNIX could be loaded as well. There are BTW, lots of variants of UNIX and it is extremely popular among computer nerds and server operators.
So, what you're selling is a terminal. Those are nice, but very few people are interested, or have much use for them. I've got one that I picked up for nothing a few years ago. To some people they're worth good money though, especially when clean and shown to be working. People often pay $50 - $100 dollars for those. Keep in mind that the shipping cost is going to be a bit steep for this as well, so the buyer will be considering that as well. Anyway, good luck!
PS: If you're interested in computers, this could actually be a great opportunity to learn about how to set up and use this kind of system. That way you'd really get your money's worth!