The "I will help you increase your profits by 200%" plumbing gurus have been advocating this for years. I guess they are starting on the electricians now. The way it works is that since you have $60.00 invested with them, any one else who bids the job has to be a lot cheaper. IF they are only $60.00 cheaper, then the customer will be paying the same as if they had the original company do the work, (which is what they are counting one). In addition, they are counting on the average person's reluctance to appear "cheap", so as long as they are already at the job site, the customer will take their price, rather than take the time to get a second opinion, and maybe "hurt the contractor's feelings". One employee of that type of company asked me for a job once, because he said he was tired of people slamming the door in his face when he gave them the price for the job.