I don't know how long I've had some of my buckets, maybe 10 years?
Some did get scratched and so I relegated some of them to grain storage, but I know that at least a few of them are 8-10 years old. I'd guess that my two favorite ones, 8 gallon buckets, have probably each done 100 batches or so or more. I brew ten gallon batches, and use those two buckets most of the time.