Arg!

Anyone know where/how I can get a replacement for the 3rd disc in my Supernatural Season 2 box set? All the other ones are fine, but the 3rd disc is scratched all to hell, I didn't do it, and it's been too long to return it.

I know places used to sell single discs as the show aired, but I can't seem to find any online. All I see now are the full box sets. Help? Please?