I am a Regional Maintenance Manager and I run into the same thing. I have a list of vendors I usually call for bids, but that list rapidly changes due to either they don't win enough contracts or just too busy to take on any more work. Like us, most vendors are facing a Labor shortage as well and not many are willing to spend the time to bid on something they can't take on anyway.
My only suggestions to help get better results: Have a clear and detailed work scope, price matrix and provide as much detailed information to the vendor you can to limit the time they have to spend on providing the quote. Outside of that, it's just finding the ones who are ready for additional work.
