Here is a theory used in other industries, perhaps it would apply in ours....
lowballers receive calls from "shoppers" people mostly concerned with price. The lowballer may be able to complete the job to satisfaction, but will not make any profit, he will go out of business. He arrives at the "shoppers" house and doubles his/her "special price", customer says thanks anyway, but no. Either way, those who are credible in this business will perservere over time by being honest and explaining to every "shopper" "our industry supports a min. $75-$100 / hr, and if they get an unbelievable quote tell them: "You should hire them but be aware , you get what you pay for"
my 2 cents