Google Workspace (formerly G Suite) has an unlimited storage plan for $20/month. You might have to contact them to sign up for it. The plan is called Enterprise Standard.
Of course it's not especially wise to switch from a gutted google product to another gutted google product, but there aren't many good options for high capacity cloud storage at a reasonable price.
The only other company I can think of is Amazon which provides unlimited storage if you pay for Amazon Prime.