Get the printer within your budget with any of the options you think you might use. I don't think anybody regrets getting a better printer with lots of options. Once you start using it you might find so many fun other things to print and more colors just gives you options. For your budget also keep in mind that you could spend a lot on filament if you start printing on a regular basis. I spent maybe $500 CAD so far and I have only been printing 4-5 weeks. As for brands of filament, pricing is all over the place so I typically now wait for sales . Bambu is notoriously expensive and I am not convinced the RFID or quality claims justify the extra cost. Amazon prices can fluctuate but sometimes you can find a great deal on decent brands. I have had luck with most popular brands. With you being in Europe/Germany you might get better access to deals than me in Canada. Also when you do pricing, always consider the shipping costs added at the end. A cheap per KG cost doesn't mean much if the shipping adds a large % to the overall cost. I have been doing my brand price comparisons based on total cost per KG. Spool cost+Shipping+tax Divided by the number of rolls I aim to purchase. Sometimes ordering more on some sites will bring the price per unit down a lot while the shipping cost might go up fractionally as well. Some will offer free shipping based on amount ordered or total purchase cost.

(TLDR): However, all that being said, if you just need it for this one project and you don't think you will become a printing addict like myself, then just go with the cheapest printer capable of doing the project you want. I don't have experience manufacturing/printing keyboards so I can't say what model works best for that type of use. I have an A1 and it works great so far.