From Stratojet website looks like another imported china machine with some in house upgrades. Many companies are doing this now, we own a Fluid color and its a similar setup, CET as well. 90K doesn't seem bad for a 4x8 UV, with the 3 head setup you would be printing a full sheet every 10-15 minutes. Im guessing for this price your getting Rich gen 6 Heads ?? If its Gen 5, that its not a good price. If your gonna do any testing I would run the machine in High Quality mode and see how the results & speed are. With a 3 head setup you most likely wont do much in there production mode other than Yard signs, not enough heads to get the full speed. We have a 3 Head system and it works fine, Full 4x8 prints in 10 - 12 Mins. I can get them down to 6 Minutes but the color aren't as vibrant.
If you haven't owned a Flatbed, Beware they need alot of maintenance and care to run at there best. We run ours atleast once a day, we skip Sundays - Not to scare you away, just something we noticed compared to our other equipment.
Cant leave it sit for a week, you'll have a very expensive bill if you leave the heads unprepared for long periods of time.