You can check out eBags.com. I think they have a ton of good deals on tigerdirect too. Timbuk2 has some awesome bags, but they are pricey. Target has some cool laptop bags at a resonable price.
I am looking for a netbook case. I'm trying to figure out whether to get one for just my netbook- I have an acer aspire one or one that holds a standard size laptop to hold my papers also. Anyone have any advice?