Hey Kat. Book 8: Robots,
IIRC, had the lowest number of copies printed of all the
GDW Traveller supplements. There are a couple of threads around these parts with exact numbers if you want to search for them. So in answer to your question, it is pretty rare. But
IMHO, $60 is about double what I would have expected it to go for...especially in that condition.
Book 7: Merchant Prince is also fairly rare and will fetch a higher than normal amount than most of the other
GDW Traveller books. Just so happens I still need that one to complete my Traveller collection and was just outbid on one from the same seller. But it at least went for about what I expected it to ($19.50).
You should be able to get a copy of Robots on Ebay for around $20 - $30 if you are patient. Or if you can manage to get to GenCon you might be able to grab one for a lot less than that. I picked up mine last year from Crazy Egor for $8.

You don't like your job, you don't strike. You go in every day and do it really half-assed. That's the American way. - Homer Simpson