Trying to shoehorn ideas into a specific type of business model is not going to get you anywhere.
I'd say don't even think about how you're going to make money at the initial stages of brainstorming. Look for a legitimate problem and solve it, make sure the people you're solving the issue for see value in the solution your providing, and on your journey to solving the problem you can then start positioning your company as far as what business model route you want to take.
That attitude is just going to lead to you rejecting a lot of good ideas because they'd be offered as free services, or you settling with a crappier idea just so you can start heading down the business model path you want to take, and you worrying more about the business than the problem is going to show in your product.
The consensus here is that ideas aren't worth anything because they are found so easily. But if that's true, then there must also be ideas that meet all the requirements. Roughly: (a) solves a problem (b) fun to work on (c) meets a demand (d) people willing to pay for it.
For me it's impossible not to worry (or at least think) about the money. If I build a free web service and need to expand to more than 2 servers then money becomes a serious issue already.
Take Reddit for instance. It was a good idea in the sense that the founders got to a successful exit. However, I wouldn't be able to expand after the first 3000 or so users, and would have to shut down. I don't think Reddit has made any money in the first couple of years, and they burned through $100.000 (crunchbase) before they got acquired. And a website without graphics that basically displays a bunch of links... that's really inexpensive to build and scale.
But you're worrying about a problem you don't have and probably won't have. If that's your reasoning behind not doing "x" then I'd argue that you may not be cut out for being an entrepreneur. The entrepreneurs I know tend to be the ones who try to find the way to make it work instead of the type who pessimistically rejects an idea because of the types of reasons you give. Reminds me of a conversation I had recently about taxes - I groaned that it was tax time and the guy I was talking to said that he liked being in the lower tax bracket because he gets a tax refund every year.
I'd say don't even think about how you're going to make money at the initial stages of brainstorming. Look for a legitimate problem and solve it, make sure the people you're solving the issue for see value in the solution your providing, and on your journey to solving the problem you can then start positioning your company as far as what business model route you want to take.
That attitude is just going to lead to you rejecting a lot of good ideas because they'd be offered as free services, or you settling with a crappier idea just so you can start heading down the business model path you want to take, and you worrying more about the business than the problem is going to show in your product.