I've implemented a very nice word to html converter previously but market research have shown that people are barely willing to pay for such a service. Maybe related consulting services can make it worthwhile for you. Good luck!
I did talk to some companies who could use it to speed up SEC/EDGAR submissions, but they were trying to get it almost for nothing and still wanted customizations.
Customizations..? Is this sass or stand alone package?
If it's multiple companies and they all want the same thing, I would do it.
That said, it's all about business development. Gotta put your sales hat on! Tell them you can do customizations but to match their price, you'll have to do recurring $y amount for at least z number of months with the first 1 month free for trying it.
Of course I'm making a lot of assumptions about your want of adding features and giving the first month free...gotta start somewhere!
