[brodouevencode]

A roadblock you will encounter: common white label services are already freely/cheaply available. Blogs, guestbooks, all the Web 2.0 things. This will lead to "why should I pay you when X does it for free". You'll need to find a way to differentiate and add value. Most of the players in this space have consolidated and now are operating at scale. Honestly, you should have jumped into this 15 years ago.

If you're referring to custom development but with a fixed scope, good luck with that. That's the whole job of a PM - you may want to get some help with that if you don't have experience in doing it.