Greg,
I'd like to correct you misconception on the cost of filing a provisional patent, and subsequent costs. Below is a screenshot of the fee summary from my most recent provisional filing (10-02-2019). You'll see it's only $140.00 for "small entity" status, and would be less than if I had chosen "micro entity". I did not because mine was filed by my firm, which is a small business. An individual can file as a "micro".
Provisional filings must be updated to a "normal" filing within one year or they will be lost. The cost of the updates for the last two "normal" patent filings I've done is approximately $7,500.00 each, using professional patent law firms in each case. Payment of maintenance fees has been required thus far on neither of these . The first of them was awarded Dec 25, 2018; the second is still "pending".
Mike