Depending on how complex any application would be... assuming you are a 1 man shop with no financial backing lets assume it is a small single focused product.
The Microsoft model for web based Access and product sales might work.
One deployment, a model for charging and distribution.
Microsoft is discussing a system to deploy what they call App, it can be a database, a photo, an e-book. MS takes a charge per transaction.
As usual, it is the marketing and other maintenance that makes the difference.
As a member of a non-profit foundation, we create unique content for distribution. Still in the process of wrapping my mind around MS fuzzy plan. I am still not sure if MS has it's act together.
The real key is to have a solid marketing, distribution plan in place before packaging the product. There are a lot of good products out there that became free-ware.
Prove the market then invest in the product. It is like building a bunch of houses on the edge of town and finding out later if there will be roads, electric, water, and commuters. Economics 101 should state: Demand and Supply - not the other way around.