I bought a Canon 24-105 f/4L USM IS lens via craigslist. I took some sample shots before I bought it and all seemed well.
The first time I used it beyond the sample shots caused me some grief. After about 5 or 6 shots, it threw err99 just about every time (1 out of maybe 20 attempts to take a photo succeeded once it stared to error). The symptoms are just about exactly described in the first post in this thread: https://photography-on-the.net/forum/showthread.php?t=787397
Basically, the autofocus would often engage/disengage with the indicator in the viewfinder turning off and on and the lens physically moving focus back-and-forth constantly, and just a bit and would continue for a second or two after I stopped pressing the button. The aperture would read 00 while I was attempting focus.
I took it to a local reputable shop and, naturally, it wouldn't fail. The fellow asked his in-house repair guy what the average cost for repair would be and the reply was $300-$400. I've seen most posts indicated about $150 + $30 shipping/handling. I'm thinking the shop is adding quite a large mark-up for their handling.
I found http://www.precisioncamera.com/ and am wondering if anyone dealt with them. The on-line quote was only $101. I haven't found any text (yet) to see if that's just to look at it and that fee pre-paid fee will be deducted from the final repair or if they really are that cheap. They do have a note that physically abused items will need to be reevaluated for cost.
What do you think? Can anyone vouch for precisioncamera.com? Should I blindly send it in to Canon directly (I'll need the shipping/contact info - the google search I did is how I found precisioncamera.com, but not one for Canon).
The seller offered to pay for repair, but $300 is a bit much and I'm not going to consider mail-order repair if I don't have any references.
If things don't turn out, she offered to refund the full price I paid.
The date code is UV08xx if that matters (bad batch/common failures with lenses from that time period)