Help with selling price of used single head

We bought out another company and along with that came a Tajima 4 head, Tajima 2 head and a tajima 1 head. We are looking to eliminate the single head and got to another 4 head. I have been online trying to get an idea of what to ask. Can anyone help? It is a Tajima TMEX C-1501 (15 Color) single head manufactured in 10/1999, excellent condition and we just had it completely maintained!