We bought our lottery ticket last week. After releasing our app we got picked up by some big blogs but when the buzz died down, we immediately saw a dip in sales. We don't have a budget for marketing but we did notice that when your app is of a sufficient quality and you tell passionately about it, reviewers are willing to write about you.
It's a roller coaster ride, but nothing beats seeing people enjoy your product.. America watch out, next week we will targeting you with our marketing :)
Plug: www.invyapp.com