I have a locally available Camaster Stinger III. It's a 4 X 8 machine with a three head setup. Whats the benefit of the three head arrangement? Is it an alternative to an ATC system? What's a fair price? He says it was $18,000 new. He's discounted it a lot from that amount. Nearly half. He did say it needs a new vacuum system. Any input on whether this is a good system? The good thing is it's only about 20 miles from me. I should add that they had to move it into storage because of the flood of 2019 and they lost the use of the building it was housed in. I'm unsure of the hours. What things should I look for if I go to inspect it.