They are ets beds (
www.etstan.com ). They have received a bad rap over the years on these boards, but, that is a whole different story. However, today they are owned by Ergoline, a world leader in the industry. They are good beds for what you need, but models discontinued, replaced with newer, better as seen on web site
If the 3 laydowns, the Starpower, Solaris 336, Sunstar are a total of $4500, and beds are 5 years old, I'd offer $3800, no more than 4K. Much depends on condition,# of hours etc.
Most likely the lamps would need changing. In fact, unless they have a few hours on them, change them anyway. That could be an expense, at about $18-22 per lamp. There are 36 lamps in the Solaris, 32 in Sunstar, and I believe 48-52 in the Starpower...so do the math. That does not include facial lamps.
I would skip on the Sunstar and standup, if you were set on these beds. Hardly anybody uses a standup
You may be better off buying pre-owned newer beds from a reputable dealer, which could include a warranty and set-up. You need to be sure you have the required power and AC to run these beds. Another reason to go thru a dealer. They could better advise on need.