Hello Tia,
The problem is that there are no regulations, there are no laws or statues in any state in the USA or elseshwere that establsih what it required to be a professional domain broker. This is all to my knowledge. So, what are you looking at are professional domainers that are either well conntected or not. None of them have any quals to speak of so your have to go on a few things. I would consider these things to be important:
1. Honesty - gets your domains noticed with lying about traffic or something
2. Ethics - part of honesty but moreso will deal fairly to all parties
3. Brokerage/sales background - working in the best interest of the party that hired him (seller/buyer). A broker/lawyer will know how to handle his fiduciary responsiblies correctly and having a sale background is self-explanatory
4. Experience - if any, domains sold by this broker or deals this broker has been involved with
I'm sure I could list a ton of others. I am a real estate broker, so I understand brokerage itself. It is good that this industry is not regulated, I love it. Real estate is too much but the laws are in place to protect average citizens and in this case you have no such protection. I would consider the above four factors items as a starting point to determine if you like the broker you are working with. One other thing, listen to your broker, if he/she says you names are not worth what you are asking then they may be right. While you are thinking emotially, they are thinking objectively. Cheers,
Acro