Why would you want a nice business application written just for your business? The short answer is to save time, and save money!
I can't tell you the number of times I have seen someone use an off the shelf product to print out a purchase order. Then open up Word and type a fax cover sheet. Then go to the fax machine to fax the cover sheet and purchase order. If I write an application for you, the fax cover sheet will be created when the purchase order is created and if you are hooked up to a fax server, or a modem you can fax directly from the application. Plus I can allow you to place a signature on the purchase order if necessary.
How many "boiler plate" letters are you spending time on when all that needs to be changed is the mailing address, and are you getting the labels printed along with the letters?
Want to do an email blast to all your customers at one time, or how about sending an invoice via email? All of these tasks can practically be automated. Just set up a few paramaters, conditions, and let the computer work for you.