With a website business the focus isn't on how great your product or service is, but how well you can market the website. The biggest obstacle is generating the traffic to your site. You need to focus just as much on optimization and marketing as on the product itself. If customers can't find you then you end up sitting on a great product that no one is buying.

So, yes, there likely is a need for your excel templates, but can you develop a website that will be able to compete with the myriad of other sites out there? Pick your friend's brain to learn how he marketed his business. If he started in the early years of the www he likely had the advantage of jumping in early in the game. It is much more difficult now to break in and develop a meaningful presence. But it's still being done all the time, so go for it.