
It really depends on who your customer is. Many managers have discretion up to $1000, so a few hundred dollars is not a hard sell. Above that gets into the corporate approval cycle. If you are selling enterprise software, you can get away with $2500 per seat, but then your selling cycle becomes months long.
If you are selling to consumers, maybe only a few dollars or a few $10's of dollars. Think TurboTax. Developers are the really cheap bastards, maybe $.05, But they can probably talk their managers into spending a couple of hundred dollars.
Talking with others helps with timing too. It's important to get an idea going so you can get your software built as the demand in the market is accelerating. But at the same time, by bouncing your idea off lots of people you will gain datapoints and then grow intuition about if the market is really ready for this yet. "Too early is sometimes as bad as too late" (Sandra Kurtzig in CEO: Building a Company from the Ground Up).
I've had friends who had the idea for so many things, but didn't do it -- and then someone else did. Genius is 1% inspiration and 99% perspiration. And as Edison clarified that thought, "I never did anything worth doing by accident, nor did any of my inventions come by accident. They came by work." Talking to people is part of that work.
