I'd flip things around. What if the idea is a flop and you spend ~1k talking to a lawyer, setting up all these accounts, and spending a month of effort on this work. Are you okay with that? Like, if you are okay with only getting $15 bucks for this then do it. But, I'd probably wager not, if you don't have some sense the idea is going to take off. On the other side, what if there is demand and then you cannot accept revenue ASAP. I've had that, and it really sucks, you need to pretty much drop everything and implement a cash register, and this takes time (set up company, get bank account, get stripe working, figure out pricing, plans, etc). So, I guess it really depends on if you think there will be demand, it's probably worth spending the time and money to get it done. This is a gamble though. Sorry, there isn't really a one size fits all here, it is highly dependant on your confidence that this will work. If you think it will, then invest the time.

You haven't really said if this is an on-line product or something you can go out and ask people about. Patio11 had a pretty good comment (cannot find it now) about mocking things up on an iPad and then going and asking people. Like have screenshots, flip through it with them, and ask if they would pay for something like that. It sounds like you are firmly in this area of wanting to know if it's a good idea people will pay something for. So, you probably don't want to create a company yet. Again, just guessing here. Providing more info will greatly help in giving advice.