Look, the "ports" for the buckets are just glorified PVC elbows so save a ton of money and just make your own instead of importing something. You will find plenty of articles/threads where people have done their own using PVC elbows. They are not mice proof but you can't beat the price if you...
Ah, there are no plastic ratproof feeders. Gotta be metal. Curious though, screw in type? Are you talking about the PVC elbow feeder type or companies that sell the "port" and you supply the bucket? Those aren't ratproof either. Rats can and do jump dozens of times their body length...
This is the thing about having proper feeders, you pay for them even if you don't have them because they prevent so much trouble and waste. Having feed available 24/7 keeps all of the birds well fed and allows a flock owner to have more flexibility as far as not having to be there to feed the...