hey, brad... i put down 5 calls a day precisely because it was a very conservative number. i don't think it's wise when doing revenue estimates to use anything but the most conservative numbers. that's also why i plugged a ten minute conversation in about each call.
anyone who has ever bought or sold a car knows these can be very long phone calls. you have to cover a lot of ground about the mechanical condition of the car, but you also have to gather enough information about the seller and/or buyer to see if you trust them.
i would say most calls would last about 20 mins, and that in many cases buyers and sellers would use the service more than once before meeting and closing deals. what's the upside estimate? probably $3-4M, just on this one deal alone.
the best part of all is that for each customer the costs are very low, so it represents a compelling value. who wouldn't pay somewhere between $1.50-$5.00 to buy or sell a car?