^You might want to link thats store because Ebay is very risky. bhphoto.com and adorama.com are both reliable stores and either have the S3 new or used for a nice price. Another place to buy used from people is
www.photography-on-the.net/forums and scroll down to the market forums and sell area. YOU can post that you want to buy an S3 or just look. They are there.
B&H right now has the Canon S3 for $294 jsut the camera. Check around for SD cards. They just had an awesome sell. I got 2GB Ultra II for $40. The site I listed is great for Canon users and even just camera users in general because we all watch for sales and post about them so if you're in need of cheap SD or CF cards, we know about it.