Before you should start shopping for an amp, you need to know which sub you want. Which model from JL are you looking at? Then mate those specs with the amp.

Some people really like Adire. They having a cheap budget sub that is said to be great. I am a fan of JL and Image Dynamics for subs.

It is not hard to install amps and subs if you are good at comfortable with taking panels out of your car, working with running wires throughout the length of your car, or working with electrical power. It is actually easy enough that someone online can give you a walk-through.