There are billions of fonts out there, but how do you decide whether to look for free fonts or paid-for fonts?
The main decision is about uniqueness. Are you going to find the font you have used all over the place? Does it matter? If you are creating a professional publication for print or for the web then it probably matters a lot.
But is there anything wrong with using a free font? Absolutely not, and there are plenty of good ones out there if you are willing to look. Make sure you check the licence agreement to make sure it's OK to use your free font for professional purposes.
The real advantage of paid-for fonts is that you can find exactly what you want. There are more of them available from the big font publishing houses, and their systems are built to make finding the font you want a breeze.