Go for the used Prusa MK3S+. People used to pay a premium for assembled and tested printers. As long as you can get the printer to you without being banged up in shipping it’s good. Really shipping would be my biggest concern.
I have a MK3S+ and it just prints. I print for my Etsy shop and don’t really feel the need for a backup printer. I have 1600+ hours of printing on it. In that time I’ve had one nozzle clog and one blob. I do a little dust filter on the filament so i don’t often get clogs https://www.printables.com/@Fohn23_807562/collections/641537
I’m totally happy with just the smooth sheet. The textured sheet is supposed to work better printing PETG but I’ve been able to get perfect PETG prints on the smooth sheet using windex as a release agent.
I print FDM. I’ve paid for the printers and make a little money each month. Not enough to live on but enough to finance the hobby.
My mom hooked me up with a teacher who wanted a watercolor insert for altoid tins. The lady was enthusiastic and would pay me every year to make them for all her classes. The design she pointed me to was a BSD license but I remade it anyway. I’d make like 100 prints at $5 each. Made like $500 X 4 years.
I haven’t heard from her for two years. I don’t know if she still teaching or found another printer.
I make some photographay related devices and give them away on printables/thingverse. For the most popular designs I mention that they are for sale on etsy. I know there are a lot of people interested in the things but without a 3d printer. I’m also not shy on mentioning my designs on social media if they are a solution to that person’s photographic problem. On etsy I don’t mention thingiverse/printables except for one disability related item. The etsy sales are about $120 a month.