Carburetor severely corroded inside.

This Craftsman push mower with 6 horse Honda has been trouble free and started on first pull for more than 15 years. First of year wouldn't offer to start without a squirt of carb cleaner then bust right off,run few seconds and die. Tore carb down and inside looked exactly like lead battery cable end with leaky case around post. No use in going any farther so I began searching for a new carb without any luck. I wouldn't have put 10 cents against your dollar bill the carb could be cleaned out then work but finally decided to try anyhow. After I washed away corrosion the housing was badly pitted like a cable end on it's last leg. Had you saw the condition I'm sure you would say no way but unbelievably it started on the first pull. Why you might ask would I have cussed under my breath when it came alive and ran like it had all those years? I was pi$$ed to think of pulling on 2 or 3 year old mowers in the pasted until my arm hurt. This carb is very simple and no means of adjustment so I don't understand why every mower doesn't use one like it. Here's my question. What if anything would you do in attempt to prevent corrosion returning? I have a cut off between tank and carb but wonder if sitting dry might make it more prone to corrode. For the last 10 years or so I've ran Seafoam in gas comming up on time engines will be used less often. I've never heard mention of metal corrosion caused by Seafoam but I can't help but wonder.

Not sure what others experience has been, but in every corroded carb I've dealt with the cause has been water. Some cheap carbs have unplated steel float bowls and these rust on the very bottom. And I've always found a drop of water under the gas.

Some can be contributed to people not being careful with gas cans. Some, at least IMHO, are due to the methanol in fuel attracting water vapor from the air. For that reason, non of my cans or tanks have vents that are always open. Sealed after use with a cap. I bought a bunch of the cheap plastic vents and put them in everything.

Interestingly there were no sign of rust,only greenish white substance like battery acid. The steel bowl only had a black substance which scraped off after a soak in Berrymans. The grey pot metal body suffered all the damage. I couldn't remove brass jet due to corroded body but it required alot of effort to push a tip cleaner through after several hours soaking in Berrymans and PB Blaster.
I hear you on modern fuel and fuel cans,I wish we could find a better way to support corn farmers. I have enough old style cans to last until I turn 120.

It is pretty common for aluminum to corrode when close to water. There are two schools of thought about storing a carbureted engine. One says to put stabilizer in the fuel and store it with the fuel in it. The other says to run the carburetor dry. I have tried both ways with mixed results.

Ultimately, now that corrosion has started in your carburetor, I think you will probably find that it requires cleaning on a regular basis. Hopefully, not more than once a mowing season.

You might check with a Honda dealer. Some of their carburetors for the most common push mower engines are pretty cheap. That said, Some that seem very similar will cost way over $100.

All things considered I think you are correct, continuing to search for a replacement carb would be wise.
As you say,there's little doubt corrosion will continue and a particle the size of a gnat's eye will block the jet and shut it down on the spot. I'd much rather spend time resurrecting an old tractor than monkeying with a lawn mower.
On a side note Honda has earned my business. Thinking back I recall a bike,4 stroke outboard and a pressure washer that gave me outstanding service.

Look on Amazon for cheap carburetors

There's no shortage of cheap carbs,the problem is finding one that says it will fit this application.

If you know your engine model number I'd look for carbs on Ebay. Their sort feature works so much better than Amazon's making it easy to compare and some sellers list a lot more details than others on things like this. I see a bunch for $12 to $15 and some include and entire tune up kit (carb, air filter, spark plug).

I had a few with that green gunk and corrosion. Be nice to pin point what really caused it.