Dont immedately think you are being ripped off, I hit a BMW up the arse in an S14 200SX once - the bumper on the 200 was dented but there was no apparent damage to the Bimmer. Agreed that he would get it checked over, he came back saying it needed loads of work, my first thought was "taking the ****"
As it happens it went to a mates bodyshop and really did have about 4K of damage, the 200 was written off as well, so about £7K from a 5mph shunt that didnt seem to hurt anything, its easily done.