The problem is that when you're forced to sell your product for $0.99 (actually $0.69) none of the traditional marketing methods are cost effective. So the only way to make money is either getting mainstream press coverage, or having Apple feature your app. Both of those are random events unless you have a brand name or a big marketing budget.
The bottom line is that publishing an app is essentially playing the lottery.
You don't necessarily have to have a huge marketing budget to get you app out there. It's possible things like freebies and word of mouth to get you product off the ground.. that is assuming that it's any good.
And if you have a particular niche market/customer base that you are aiming at you should already know what forums/places that they frequent. Just figure out a way to get the message/word of mouth to them. Offer a limited amount of 'free' copies as a 'beta' test round or something. Make sure you have an open dialog if it is a close-knit community. Or consider purchasing some sort of targeted advertising on those particular sites... It's not too hard to come up with a laundry list of things to attempt.
I'm sure that people smarter than I at marketing have book galore to peruse... People complaining because the AppStore isn't doing a good enough job of marketing _for_ them don't gain any sympathy from me.
The bottom line is that publishing an app is essentially playing the lottery.