How much do I charge for a 2 Head Tajima?

I have a 2 Head Tajima Embroidery machine that I'd like to sell. (Keeping my 4 Head.)

Problem is, I have NO IDEA how much it's worth. I've looked at Ebay and called a few sellers of used equipment, but they won't even talk to me! Sheesh.

I have an interested buyer, but don't know what price to ask. Ideas? It's a Tajima TMFX-C902-S -- about 18 years old but hasn't been used much and works fine. Thanks!