How to justify product idea?

I second Ash's recommendation to follow the customer development process. One entrepreneur using these principles, mocked up screen designs to show prospects what he was working on. After you have that, make a concerted effort to find early adopters. Reach out to them and interview them about what you have in mind. Test your core C-P-S hypotheses: Customer-Problem-Solution.

I am have had experience of a similar problem. In my opinion, The only way that you will find a launch customer for an as yet unbuilt product is through contact that you already have or perhaps customers that you have sold previous products to where you have some trust built up.

Other than that, the choice I faced was to build the product first. This is a real test of how much you believe in the product. Have you fully defined what pain your product solves and who for? Maybe you should moot this with contacts you have who may be possible customers and see what they say? This forum could be a useful place to debate any elements of the idea you are unsure of.

In our case, we built the product (released as early as possible) and then found a number (in our case 20) beta testers who were willing to try the product in their business for free for 6 months. In return, they had to give us development feedback and more importantly testimonials because for effective sales, you don't only need a product to show but ideally case studies to prove it works.

Good luck....

Check out the book Crossing the Chasm. It has some great recommendations about user adoption and how to introduce your product to market. Im with Jeff on this one. You really just need to build the minimum you can use to display the product. Don't display the unfinished version to fence sitters though. try to find people that are enthusiastic about your project and work with them. They will be more forgiving of errors, glitches, bugs, etc. In addition they will likely give you the best and truest criticism. As Geoffrey Moore explains in his book, you will be relying on these early adopters to help spread the word later on, so why not get them into the fold early...

Hope this helps. I highly recommend the book!

Build as much as you need to get in front of them and show why yours is better, you know what you're doing, and you are capable of building it.

What are their expectations on converting data from an existing system? Do they expect you to integrate your app with others? You could get this information by making a few calls.

As a side note, get the first page/form to load up as fast as you possibly can. Even if that means limited information. I know the people on the customer side of you customer-service software are not your target market, but the service experience would be better if we don't have to wait so long for them to pull up an account.

Good luck and keep asking questions.

I wrote a post about this

http://000fff.org/a-simple-model-for-innovation/