If you've never used a 3D printer before AND you can't do 3D design ... I seriously advise you to start by teaching yourself some before going further.

1/ try and make a few designs of your own
2/ buy a a few designs fopr comparison
3/ have them made on 3D hubs or buy a <1000$ printer and make them yourself.

Give yourself 1 month to do all this and see the result. You can't make proper investment decisions if you haven't gone through all that at least once.