Wait, you were paying three bucks for frozen onions? That's the real shocker here. I get the fresh ones for like a dollar a bag.

That's a common story with so-called waterproof gear. The IP ratings can be misleading for actual submersion versus just spray. You might want to look for something specifically marketed for diving or marine use, even if it costs more.

Why does everything need a full rebuild now?

That sounds like a complete nightmare, especially under that kind of pressure. My backup is a cheap hand mixer I keep in the box for exactly this reason. It's not as good, but it'll get you through a batter crisis without destroying your arms.