There is a simple way to do this. Use a virtual phone number and a contact form with a unique e-mail address. Make your agreement with the dentist, and anyone contacting the dentist thru the virtual phone number or the e-mail address are yours, and simply ask how the customer found the business. Your virtual phone service will track each call made to the site, including the number it came from and how long the conversation lasted, so you have some records to use for an audit. Any cheating will show up as a pattern in the audit.
Make clear in the agreement that you can audit the books at any time, and you reserve the right to discontinue supplying leads at any time for any reason. This is necessary because you never know hat might happen. The are wonderful customers and flaming buttheads. Google could de-index your site. Leave your self an out and never promise all your leads to one person.
If you are bringing a professional work, they are not going to mind paying you for your service any more that you would mind paying for ads in a PPC campaign. Its a matter of money in this end, and more money out the other end to them, and its not worth their time to game the system, (the logistics as someone said above will be staggering), unless they are a blithering idiot. Don't do business with blithering idiots.
He is not the only dentist in town, and if he screws you over he should have enough sense to know you will find a new buyer. In fact it is in your best interest to not obligate all your leads to one doc. Spread them around and see what the market will bear.
Make whatever deal you want with doctor one, and send him leads. Approach Doctor two, and offer the leads at a 10 to 25% higher rate. If he bites, offer Dr. three a higher rate still. At some point you will hit a fair market value ceiling. You will now be able to get maximum revenue for your product. And you don't lose the customers you already have.
Expect to make a much smaller percentage if you get a deal for subsequent recurring commissions, and a much higher rate for one time payouts.
Flat rate brings you money for every lead, making it easier to track and manage. Selling by percentage makes you far more money.
Doing both is a real winner, drop your per lead fee down to 75% of market value and ask for 3 to 5% of all work generated for the lifetime of the customer. For some reason people dismiss percentages below 5%, as if they do not add up.
This way, you get immediate cash flow and develop a long term revenue stream.
In the beginning, if you are selling these leads at a flat rate, at least go to service magic or similar sites and pose as a business owner and find out how much you have to pay for the exact same lead in your area.
If your price per lead is lower than that, you are competitive. If it is markedly lower than that, you are leaving money on the table.
I expect dentists are high, in Houston a tree removal person pays $38 and their value per customer is a thousand or two on a one time basis with about a 20 percent conversion rate of calls to customers. (Just talking to a owner yesterday and this came up)
good luck there! Update me if you don't mind.
