I don't really see the market.....
You would service one airport? Operators would already have their own procedures in force to obtain their flight plans etc.
In the event the company wished to outsource their flight planning.... Then they would go to (insert name of flight planning provider)
Now considering you would have to have a licence from the said flight planning provider and 100's of aircraft and engine combinations subscribed to it would cost you an arm and a leg... In short no way you could do it cheaper than the flight planning provider.
PT6A