I have a 24-70L 2.8 here just back from CPS. I'm switching to primes only, so my zoom is up for sale.
I sent it to CPS last week to ensure it is optically perfect. They did some sleeve modification and updated some internal pieces. Cost me $188.
So you could look at my price and say... it's a bit on the expensive side. But you get he piece of mind knowing it's perfect and it won't need service for a long long time.
Pictures:$1150. shipped and paypal.
Price is firm, no trades at all!
I invite any serious buyers near Boston, to stop by and test it out.