Certainly you won't be paying $10,000 to $20,000 for a brand new one. You could easily pay $1000 for a used one at a retail establishment that sells the plotters they take on trade-in.
I suggest that you find yourself a nice Hewlett Packard Designjet Plotter. The 220, 430, 450, 600, 650, 750 are all great plotters that are about 15 years old. HP shouldn't have designed these so well, they live forever...and they hate that the secondary market cuts into their profits. But they are magnificent machines that almost never die...Except for belts and trailing cables.
Craigslist always has a number of plotters listed in the area, why not just pick the cheapest and be done with it? Because of what I just said: Belts and Trailing Cables! These are the two items most likely to breakdown with age. 98 out of 100 Designjets with their original carriage belts will have a belt breakdown in the next year....most within the next 100 plots! About 40% of these Designjets will have their trailing cable begin to delaminate this year. Both of these parts will require a replacement that means someone will be taking the machine totally apart and replacing both things.
So, don't buy from someone who doesn't seem to know anything about plotters or the guy who says "It has been sitting in my garage/basement for the last 7 years and now I want to sell it." Both of these people probably have a belt failure looming....and you will be the proud owner of a big ass HP boat anchor!
Buy it from me and you'll be guaranteed that the belt won't break and the trailing cable has been checked and replaced if necessary. You can also be sure that the machine has been totally cleaned, the ink spittoon has been emptied, the plotter has been reset to factory calibrations for perfect lines and total accuracy.