You can check out the world of micro-ISVs (indie software developers). It's been tough in the last 5 years or so, because everyone has their own web site and are trying to reach a wide consumer audience. Just browse the spectrum of questions on http://discuss.joelonsoftware.com/?biz.
You are correct about the cost of the Mac and iPhone. But a lot of students I meet already have a MacBook.
Also, entering the app store costs more: you also need a Mac and at least an iPod.