I have done the trip a couple of times now.........if you have any questions PM me. Also if you plan to drive up, I might be able to save you some $ on a raft rental.
Driving up would be nice but it adds 10 days to the trip. I've done the ALCAN a few times and it is long driving. Gotta pay attention on that road especially up near the Yukon. By September the road work should be winding down farther north which could ease the time.
$4K - 6K is what I was figuring from my research which is completely reasonable when you think about being able to make it a 2 week trip if you want.
I spent 7 days going up and 4 days coming back, yes it takes time for sure but it is one of thee coolest drives I have ever done (once you get through most of BC). With that being said, I'm not quite ready to go back yet.

For cost, my 1st hunt was roughly 10K, ( we went to a pretty extreme place) and the 2nd was $4500 with a buddy who lives there. Anyone who gets by with less cost and is successful, congrats!