Yep the bearing is numbered 6203.
Just walk into any car shop or bearing shop and ask for a 6203 bearing.
Make sure you get one that is sealed on both sides.
There are also high temp ones available, which cost a tad more.
Should be less than $10 for one.
I can't quite remember how I got mine out.
I think I used some fine pliers and tried to compress it together a bit at the lumpy ends where there would normally be holes to use circlip pliers.
I then shoved a small screwdriver in behind the clip and levered it out.
I do remember it was a PITA! :p
I have heard you can clamp the pulley in a vice and drill tiny holes into the circlip and then use the pliers.
The same bearing is also in the a/c tensioner pulley above the idler one, so might be best to change that one as well ( I think that one has a normal circlip).
