Purchase Games Online
Like everything else, you can buy German-style games online. It's definitely worth doing some price comparison between sites, because you might get a deal if a retailer is trying to clear out stock on some older games. There are several stores in the Seattle area that sell these games as well.
Boards & Bits
Founded by a gamer guy that used to live in Woodinville, this online store usually has good prices and stocks some games that might be harder to find (or more expensive) elsewhere.
Gamefest
This is another local company, based in Issaquah. They seem to target a more general audience, and focus on more than just gamer's games.
Funagain
Based near Portland, this company has been around since the early days of German gaming popularity in the United States. They have a huge inventory, and often have obscure games in stock. However, all this choice comes at a price -- most games can be purchased elsewhere more cheaply. In terms of the resources available on the website, and the overall quality of the site, service, and shipping, these guys are the Amazon.com of games. Even if they don't stock a game, they can usually find a copy and sell it to you if you ask!
GameSurplus
This smaller company is similar in scope to Boards & Bits, but is based out of Pennsylvania. They are worth a look when doing price comparisons.
Boulder Games
Although their website is pretty horrible, they stock a decent quanitity of games. They tend to focus more on war games, but have a variety of other games as well. Sometimes they have good sales!
ADAM spielt
If all else fails you can go straight to the source. This online retailer in Germany stocks all the latest games as soon as they are released -- sometimes even before they are officially released. If you don't mind dealing with Euro conversion rates, large shipping costs, and delays up to a month, and the latest selection is important to you, then go here! (The best way to do an order is to get together with other people and make a single, massive order, and split the shipping costs fairly.)