Well, most of the discussion to date has been focused on hourly pricing, as opposed to fixed pricing for "shrinkwrap."

Without more details about the product itself, it's tough to say what a fair and reasonable price would be. That said, there are some things you can do to get some help.

Have you researched the market? Have you defined it? Who will your primary customers be? Corporate customers have deeper pockets than consumers (a fact a certain PC software maker seems to have forgotten). If your software could potentially, as jepri suggests, save a company the cost of a single employee's salary, cost, overhead, etc...then you might be able to get away with charging pretty severely for it, perhaps $20K-$100K for a server-license.

On the other hand, if your product is a personal consumer device, then you're looking at $10-$100, depending on its function, value, and competition.

In addition, you need to determine who your competition is. What are they selling and how much does it cost? Use that as general guidelines. Once upon a time, certain compilers sold for $500-$800. A certain company came along and sold one for $75--1/10th the cost of the one from their biggest competitor. They did well by it (until they bought the wrong company, but that's a different story.) The point being that you might consider undercutting your competitors.

Also, consider your licensing strategy. Are you going to require licenses for each CPU? Server? User? Site? Each offers interesting variations on pricing alternatives. Again, find out other companies that are using similar schemes and what they're charging.

Finally, keep in mind that you're probably not going to be "fairly" compensated for your personal time and effort. While some authors command good livings from their efforts, most don't. Or, as they say in acting circles: "90% of all actors are unemployed at any given time." My point being: don't bet the farm on this endeavor. It might, indeed, be the killer app that catapults you to the top of the Forbes list. Odds are, though, it won't.

--f