Suitable Business model?

I have created a prototype for an application.

• I know there is a market for what the application does as there are existing products that have same target audience.
• Existing products are VERY pricy.
• The product is simpler and easier to maintain than existing products in the market.

I just have one problem. How should I put this to market?

A way could be to make it open source. This has worked for me with plain. Plain was however a theoretical experiment, a playground for thougths on how simple and easy application architecture could be made. There was never a plan for a final release because the process was more important. The no limits and no constraints meant that we could implement a search filter framework that resembled Linq a bit before we ever heard of Linq. A validation framework much like the one now found in nHibernate and ASP.Net Mvc 3 etc.. But plain intentionaly lacked one thing that I would like my new project to have. Exposure and usage.

• Open source the product and commercialize tools and support.
• Open sourcing everything.
• Make everything closed source.
• Some others I haven't thought of.

This is a more finite problem and I want to work towards a releasable codebase. Will a enterprise product ever be popular if it is cheap?
Will it be possible to have a differentiated licensing model for hobbyists and enterprises. Will this model result in a greater usage? Is it at all possible to have the kind of openness and transparency I'm looking for if the project is not open source?