No , I have not heard of them, however I did check out the link you provided , personally you will find all the information on my website if you take the time to study the process and not costing you a penny.
I can help you along with fair price to pay and lesson the fear not ending up with a lemon if you simply provide a link to a vehicle that you may consider and have test driven.
Even if they negotiate for you, you still have to go check out the car and talk about the "extras". You have to like the car you are buying.
They want a credit card to put a "hold" on it before doing anything for you. If you opt to not give your card number right away they set up for their negotiator to call you. I am sure that call will be a high pressure sales pitch aimed at someone who has admitted they don't feel like a great negotiator and want someone to help them buy a car.
Seems like a definite way to part with $400.
Anyone use the site and have a positive experience?