Like if you don't care about using the logos or not, or having your name listed on the site as an assistant, and whatnot that come along with being classified as a trading assistant on the site, can't you just put an ad in the paper or Craigslist that you'll sell stuff for people via Ebay, under their own Ebay account?
As long as you have a lawyer draw up a short contract stipulating the agreed upon fees, can't you then sell for somebody who already has an Ebay account that they've used to buy stuff with, but that just don't want to be bothered selling?
I found a link to the trading assistant but don't see any advantage to it other than using logos - which, as a buyer, what do you care if there's a trading assistant logo or not, and having your name listed for people to contact you if they're interested in somebody else selling for them - which you can put in an ad yourself.
I'm just not seeing a benefit by going through Ebay's trading assistant, other than having to read a bunch terms and conditions that you'd have to be a lawyer to understand. I think it's a lot simpler to just run an ad yourself and take it from there.