For a single head, look into Toyota also. I have bought almost brand new looking machine (Made in 2006) for a $6300 and I have just now sold software that came with it for $1100. So it cost me $5200.
It runs great, I prefer it over my 2009 Tajima Neo2.
Only problem with them are that they stopped making them. Some spare part are low on stock, but most of them are interchangeable with Tajima (95% the same machine).
I would not go any older than a ESP9000, older models are really low on parts.