I would ask what sites she is posting your home on that costs you $350. If she is with a large company - Coldwell Banker, Keller Williams, ReMax etc then pretty much any site worth posting on shouldn't cost her extra than what she already pays back to the company.
The transaction fees are becoming more common, but I refuse to charge one. She is likely charged a transaction fee on top of what she has to split with her office, you might ask for what that cost is exactly because she is likely marking it up.
My personal opinion, she is sticking it to you, but also keep in mind, with a $150k house she isn't going to take home the full 3% or $4500. She will have to pay a %age back to her office, plus transaction fees, plus marketing expenses - color copies, advertising etc and of course taxes. So after taxes if she clears ~$2000 she is doing pretty well.
[This message has been edited by East Dallas Ag (edited 2/1/2011 10:52a).]