dude try your local games store store , we have cushioned envelopes from a disc repair factory, you stick your name n address on pop in the disc + £3 and you get your disc back nice n scratch free 4 days later.
(The machine they use takes off a thin layer from the disc, which they keep doin till the scratch has gone)
If you can see the scratch on the labeled side of your disc it is F*"ked you need to buy a new one
Hope this helps