If you are chasing down a "small evap leak" or even a "large leak" on a 03-06 sedan, I have your parts.

P0456
P0455
P0440
P0442

I was chasing down what turned out to be a hole in my actual gas tank! Bought a lot of good parts, some new and some used from a part out. Save some headache and get this, it could solve your problems.

Asking $50 plus shipping.

OEM Gas cap.
Evap purge valve (one in the engine)
Charcoal canister with all the sensors and pig tails (incase you had bad wires)

 

Still have this.

Our cars are getting older and this has most of the items you need to solve the problem. Instead of spending $50-100 randomly like I did.