When we started FIPLAB, we didn't even buy a single Apple device (other than the iMac I already had for personal use). We used my friend's 1st Gen iPod Touch to test our app on and did everything possible to not waste money without first seeing whether we could make it in this business. 3 years on, and everyone in our team is making a good living doing what they love.
The App Store today is a totally different beast and unless you are very lucky, you won't make it big without a proper strategy that involves at least a few of the following (1. securing press coverage on popular websites/blogs, 2. Having a budget to spend tens of thousands EACH DAY on generating downloads (or a cross promo network to leverage your current userbase), 3. Developing a viral app that quickly propels itself up the starts.