If the Seller has a broker I just punt my side to an agent or Broker I know in state who will represent my interests. You're going to be out the 4 or 6% regardless, you might as well get someone in there that will represent you - and get some good will with your person in the process.
This broker will say he / she is "independent" as required by state law, but he doesn't give one half of one turd about your interests. When these deals go sideways lots of complaints get filed with the state's real estate commission and then there is all sorts of CYA.
If you do keep this arrangement you need to deal with this broker as if you don't trust them at all. Don't tell them your lowest offer and then start higher - you'll screw yourself.