The printer is about 20 euro, raspberry pi zero is currently 10 euro, pi zero camera is 14 euro. I don't know how much 3d printing services cost, since i have my own printer. Powerbank depends on which powerbank you choose. Cost difference is probably less than you'd expect

While I did just buy a 3D printer, I want to enlighten the community: many public libraries now have maker spaces. I recommend checking those out if you want to do one off stuff

There's plenty of services that 3D print for you.