As in get them to pay before they can get the product?
Seems like they'll then blame you for not making the product you said you'd make, if they pay for a product that's made they can't reasonably make that objection (but could argue misselling I suppose).
When you don't charge, users who say "I would buy that" are not actually saying yes to your marketing pitch. They're usually saying "hmm, seems interesting"
When you say "preorder now!" the users who pay you money have most definitely said yes.
Some will be disappinted, yes. But, if you actually have a product, some people will still be disappointed and want a refund. This is inevitable.
What asking for a preorder does is it filters down to people actually interested in paying money for your pitch.
no, the pattern is to ask them to pay, but not actually make them pay before it's built. If they're willing to click the buy button with the price clear, you've learned something valuable about the price/value you're presenting, and you can learn that before you spend the money building the product.
To be honest, I've never been 100% comfortable with this pattern - it seems deceitful at the surface. I'd prefer an alternative that makes it clearer the product isn't available yet, but allows you to capture that same information. But I think once you do that, lots of people that might be happy with the price simply won't bother letting you know they'd be willing to pay - they just go somewhere else.
[edit]
Sibling comment talks about a 'pre-order' button, which is close to what I meant by the second option. I think you learn something really valuable with that approach, but I'm not sure it's the exact same thing you'd learn if the user thought it was available now. IDK, maybe it's _more_ valuable...
Depends on what the product is. Can you do some or all of it manually? Obviously not for a todo app on a phone (for example), so it doesn't apply in every situation.
But for some solutions you may be able to test the market via manual processes or a Zapier rube goldberg machine before spending engineering time.
