A week ago a game of darts resulted in a pin sized puncture of a copper pipe in my basement, causing a slow drip. I put some putty on it and covered it with two clamps and a piece of rubber. That worked for a little while but the dripping started again with much greater frequency and even spurting at times. I called a plumber and his solution was to replace the pipe completely; which is what I anticipated. What I did not anticipate though was the price he quoted me of $780!! I had anticipated that the price for this would be in the $200-$300 range. $780 seems quite excessive. Is this a fair price? I want to get this problem fixed properly and safely, but I don’t want to get ripped off? Any recommendations or insights would be appreciated.

That seems like a rip-off. To fix a small hole in copper pipe, all they have to do is clean the pipe, cut the hole out, and install a repair sleeve, not the whole pipe.
If the pipe is accessable, the whole job should take no more than an half hour, to one hour.
So, I would say your idea of about $200.00 would be in line with the correct cost.