Think about it like this: If you broke the heel on one of your shoes, would you buy a new pair or just replace one shoe? Think of the wheels on your car as its feet. Both sides need to be in balance! If you wore shoes with different-sized heels, you might have a limp, right? Well, if your car has different quality brake calipers from one side to the other, you'd have something worse than a limp: one side might grab harder than the other, and that could seriously affect your handling. This would be magnified under severe conditions like rain or on slippery surfaces, and could even be dangerous.
For additional assistance, please find an AskPatty Certified Repair Shop at http://www.askpatty.com/search/?type=all&m=30&q=&keyword= and they can help you diagnose and repair your brakes.