As a bootstrapping entrepreneur, my instinct has always been to work before spend. If there was a way to spread the word virally instead of buying ads, I would. If there was a way to change the project so I could do it myself, I would. If I could trade or whittle my way into getting an asset on the come, I would. That's the mantra of the bootstrapper.
It turns out that paying for stuff works too.
Ads that pay for themselves are worth buying. Employees and freelancers that produce more than they cost are worth hiring. Office rents that generate productivity, foot traffic or revenue are probably worth paying.
In the free media world in which we're living now, it's so easy to get stuck on not investing, on avoiding outlays at all cost. Frugal is an admirable trait, but being a miser is dumb.