I'm wondering if vendor sales would be enough to be able to pay for a respect at level 14 and/or level 17.

It would help for a concept character that I have in mind.

Thank you in advance for any insight provided.

With ease, if you pick the item vs the recognition medals from mission rewards to sell to npc vendors.

Below 20 it's no problem, above it gets harder.

This is total retcon, all powers replaced. If you replace just a couple of top powers (last taken) and/or don't do much about specializations its easier/cheaper.