Sounds plenty fair to me. I am not sure I could adequately explain in a simple post the things to look for when buying a used pistol. I know I have learned a few things over the years, got burned a few times. First thing, and you are doing it right now, get on an internet forum that deals with that specific brand of guns and get some opinions about what sort of gun they are from people that have used them. I currently have a 6904 and have owned a 6906 in the past and I will tell you, they are great little concealed carry guns. Someone had tried to do a trigger job on the 6906 I bought, and butchered it, so when I got it, I had to take it to a gunsmith to put it back in proper order.
Since it is an alloy frame gun, I would take the slide off and have a close look at the frame rails for cracks, if it has been shot a ton, or someone has run some too hot stuff through it, that possibility can exist. If the shop happens to have a range, see if the guy will let you run a box of ammo through it.