I'm not sure, but I know Borders has an alright SR selection, but just like B&N they're dominated by D&D4E.
Between my other half & I, we've spent about $280 on
sourcebooks alone the last two years. 90% of that was bought at my local game store, with a 5% loyalty discount because I've been gaming there for three, four years now? It's not much, but it's so nice to have someone who knows what he's selling.
Not to mention, cheapy snacks and iced tea!
Local availability low, I support the idea of Amazon. I'm a sucker for free shipping.
Also, Chessex has a ton of stuff available on Amazon in terms of dice if you don't have anywhere to get that either.