Hey!
Welcome to LA!!!
Your best bet is the Culver City folks - there is a pretty huge following out there. And one of the esteemed members here, Largent80, lives out there in Culver City!!
Anyhow, check out the meetup here:
http://www.meetup.com/The-Los-Angeles-S ... tup-Group/
Getting a jersey might be tough - your best bet, hit a Westfield mall. The bigger sports stores will sometimes carry Wilson jerseys and it looks like there are two stores out there at the Westfield in Culver City
http://www.westfield.com/culvercity/
I'd say definitely start socializing on the meetup and see if you can get some help on getting around and how to find a jersey (heck maybe one of the group members will have a jersey your girlfriend can at least "rent" ... what? fanatics having extra jerseys? you don't say..)
And Largent80 is a standup guy so if you contact him he can probably help you too.
Last resort: if you really can't leave the LAX area, I guess find the cheapest blue tshirt at the airport, some masking tape, and tape a "12" to the shirt. Then find the gates with departures to Seattle (usually Alaska or Southwest airlines) and plop at the closest sports bar near those gates.
GOOD LUCK! GO HAWKS!!