There's no reason to buy a used inkjet if you expect to be a going concern.
The only time I'd consider a used printer is if I know who I'm buying it from, and they're taking it out of production on a Friday and I'm putting it right back into production at my location Monday. If you can get the work, a new printer will pay for itself very fast. I'm all about used/cheap laminators and even plotters if you can find lightly used ones, but inkjets.... I sleep better knowing I started the odometer at zero.