Hooz & yasamoka, radioshack will get most accessories for the s3 soon. But we all know the prices, anyway i suggest you wait. Ill be getting mine soon enough from ksa.
My point is this, this connector has 5 pins and not 11. This has the same form as the s2 mhl, which needs a converter. Now it might work, but then again you might have signal/fps problems when playing vids. Be careful, and if you have the chance to try it, tell us what you think.