In his book ‘Buyers Are Liars & Sellers Are Too‘, Richard Courtney uses his long experience as a Nashville realtor to look at all the pitfalls that mark the process of home buying. 
His main advice, honesty ( on both sides) is the best way to experience a satisfying sales process.
In all my time in sales and service, this is an idea I try to stick too.
A cheap service might not end up being cheaper. An expensive one might just be hype. I try to give people my honest opinion and ultimately they have to choose. I refused assignments quite a few times because I did not feel comfortable doing the job the way I was asked to. I thought taking them would have been a receipe for failure.
I discovered the book on ‘In Bubble Wrap’.