I was just wondering if it makes sense to buy a broken lens and have Canon repair it? The lens in question is Canon 300mm F2.8 USM IS mark 1.
Per the seller, the housing broke (where the lens connects to the camera). No other visible signs of damage to the lens. That said the seller did not provide any other photos supporting the claim.
Would you consider buying such a lens and have it repaired by Canon? I guessed, the real question is, how much would cost to repair by Canon. Probably more than buying a new lens.
I think Ernie already answered that question. Nope. You do not want it.
I doubt if Canon is still servicing that 30+ year old lens, anyway. Half of the electronics are probably no longer in production, and haven't been for years and years. I bet that thing contains chips from the old "TTL Handbook".
There are places to get that lens serviced (it was in production through mid 2011 so it isn't that old in terms of a lens) BUT don't buy one that has been dropped/abused to the point of breaking.
My 300 is the first version IS and it is a great lens and was produced near the end of the first version production run. But I wouldn't buy a broken lens, these fast primes are well built and it takes a lot to break it that way which means there is an enhanced probability that there is additional damage or at least compromised optical performance.
Keep looking for one that is in working condition and not abused.