It's tough to make a living selling singles (or anything else) for $.99. To do it, you have to have a lot of volume
If you look at the "Top Charts" in Apple's App Store, you'll notice that, for the most part, the guys making the most money aren't the ones selling things for $.99.
Most of the time, it's easier to make one $100 sale than 100 $1 sales. And this usually means more money...at least on the front end.
Something to think about when you're pricing your t-shirts, CDs, live shows, etc... And if you don't have a "backend" income stream in place, it's something I recommend.
But if you do have a good backend...
There are advantages to selling things for a "bargain" price or even giving things away for free. One of them is that you're able to charge more for something else, since you'll have the credibility and authority that comes with a lot of people being familiar with your stuff.
Of course, this essentially takes you to what I said a few lines up about it being easier to sell one $100 product than it is to sell 100 $1 products. You're just doing it on a bigger scale...maybe charging $10,000 instead of $100.
The bottom line...
Figure out how much money you need to do what you want to do and run the numbers a few ways to find out the best way to make that happen.