Aaronw
I also don't have a local shop, so I get most off the internet.
HobbyTown in Fresno is probably the closest brick-and-mortar shop to you, I'd guess. Most of my purchases from them are consumables that I need immediately.
I have to second the nod for Tower Hobbies. I've placed several orders from them over the years, and they have always been superb. Decent prices and super-fast shipping (I ordered some paint from them over this past weekend, and received it today), and I once called them in the evening, Pacific Time--and spoke to a person! Being primarily sellers of R/C stuff, they don't have a whole lot in the way of detailing gear, but if you need consumables or a current kit from a manufacturer whose line they sell, they're just about unbeatable.
I placed an order from Model Roundup about four years ago, and found them decent except for their ordering system. Hopefully that's changed by now.
I've just recently placed an order from Sprue Brothers, and am waiting for them to receive an item that was mistakenly listed as in-stock. So far they've been doing all right.
I haven't purchased a kit from an eBay seller for a while, but they're a decent source for out-of-production kits. Many sellers are clueless as to how to properly photograph their kits, though, especially kits that are no longer sealed inside.
In progress: Hasegawa P-51D/K (being built as a D), Tamiya Morris Mini Cooper 1275S, Testors Kaman H-43B Huskie (held up by lack of parts)
To be resumed sooner or later: Academy M151A2 with Eduard photo-etch