Does anyone know an ebay user i.d. finder?

alx2010

Or a site that would find or suggest un-registered user names?

Pembroke

Ebays advanced search has a 'find a member' option. You need to already be logged in and you also have to copy a number code before hitting the search button. You don't have to enter a full name to see results so as an extreme example if you just put a single letter in you will get any ID that just uses that letter and close matches.

If the name you enter isn't registered you will be told that.