Had one ballast go bad, so I decided to just replace both stock ballasts with new slim ones I found online.

I had them marked which one was working and which was not, but my piece of tape fell off.

Been looking around for the going rate and it seems to be around $200 for a stock B5 S4 ballast. Since I have no use for these anymore I will sell both ballasts for $125 + shipping (or best offer). You're going to have to do some quick testing though to figure out which one does in fact still work.

PM me if your interested.