Earlier quoted context omitted.
The thing is, you cant really ask them for money too early or you'll be hearing NO too often for the wrong reasons... What you should be trying to find out is: 1. if they currently spend their money somewhere else to solve their problem 2. if your product is so much better at solving the problem, that they will want to switch.
Yes you can, you can put up a page that describes the thing, and pretend it exists, and try to get someone to click the "let me put my credit card # in already!" button. One click, a single click will not destroy you brand. And OP would've realized that no matter even with their best shot they couldn't get 10 clicks. 10 disappointed non-customers won't destroy your brand.
Okay i have a page and i HAVE to get people here with paid traffic like adwords because no one will write about my non-existent app.
So now I get a bit of traffic but nobody clicks the buy button...
Is it because i drew the wrong crowd? Is it because they don't know me? is it because adwords conversions are usually very low so do i need to pay for more traffic?
If it actually is because my product sucks, then cool.. But what do i change?
There is no way to know this; which is why i believe the buy button is not the way to go.... at the beginning.
You can still do this before you start building, but it must be done after talking to at least a few customers.
The traditional customer interviews are always the best way to start.