In a lot of business, you get better prices if you have more business with them, not everyone does this, but a lot do. Even small businesses, the cafe I go to drops off the change off the bill every time "make it $8 John" all the time.... and the coffee (for me anyway) is always superb..... And it take them just as long to make my coffe as anyone elses, but I go there a good number of times a week, we have developed a friendly relationship so they decided to do this). Now because I like the guys so much, I always put it any chang ein their tip jar as appreciation - and, they are not desperate for business.
besides interest, I think my PM & fees are my biggets expense, I get $20k rent, and pay the PM nearly $2k - nothing else costs more than per annum
of course, the cheapest is not always reliable, but neither is the most expensive, I've bought expesive crap & bought cheap stuff that has lasted longer too, same experience with businesses, the most expensive is not always the best. That cheap Italian restaurant using homemade tomato sauce is often better than the hotel restaurant charging $30 for a plate of spaghetti.
WBG Redcliffe's paln was to select agencies & negotiate a price, I guess he would check the service levels same as we did before we chose our PM's (?) and the only difference is he wants to negotiate a price