Every business loses money marketing to clients who end up not buying. My husband’s company has spent tens of thousands of dollars on marketing proposals and presentations, just to see the job go to another company. It’a part of the business.
My preferred solution would be to pay my realtor an hourly rate. Then, I pay for all the time I use up, and the realtor charges a higher hourly rate if he’s good. So a realtor is a consultant, like a lawyer. This is how I would like to do it. however, I have not seen a model like that. Being an honest person, I would not do what you suggested: pump someone for info, and then ditch that person and go low-cost.
Personally, I do NOT go to Best Buy to have the sales guy walk me through all the stereo options just to order it online or at Costco. If I consult a salesperson in a brick-mortar store, I buy from that store. I’ve told my kids often why I do this, and that we need to reimburse Best Buy (or whatever store it is) for their expenses to provide the education.