I got an SES light and the dealer said that it was a canister near the back of the car that filtered gas vapor? Does that sound correct. He's an idiot so I don't believe anything he says. Said it would cost near $300. Any help would be great. I have no idea what it is.

Did he happen to give you any trouble code for the SES light? If not, he could be blowing smoke to get your money. Make sure that it wasn't from not tightening your fuel cap after refueling or letting your engine run while refueling.

I found out that it is the evaporation vent control canister/valve. Anyone know where I can get this for cheap and if I would be able to replace it myself. I heard it is only for emissions and doesn't affect performance. But until I can get that fixed, my SES light stays on. Dealer quoted $400 with labor!

this should be COVERED under your emissions warranty. go back and give him a piece of your mind

Are you past your basic warranty? That would only be covered under the 3 year 36k miles part if I understand the warranty book correctly. That should fall under the evaporative emission control system. The ECM and cat conveters are covered for 8 years 80k miles.

Really, 8 years or 80,000. I thought after the 36,000 that was it. As a matter of fact, the ticket writer asked if I had any extended warranty. I said no and he said that I would have to pay for it. I also found out that the ticket writer got fired for "bad business practices". So this should be covered under warranty then huh?

You can double check it in your warranty book that came with your car. It's clearly stated what is covered and for what periods.