Fry's Electronics, Los Angeles
This is a huge warehouse style electronics shop that most likely will have what you want. In some ways the hugeness is overwhelming and you may not be able to find that little piece you need. However there are staff everywhere , not always helpful and friendly, but you do get there in the end. Just don't go to Fry's if you are in a hurry!
What to buy: Well, you can build your own computer with components, or buy some wonderful software packages, almost anything.
I wanted memory and battery for my digital camera. Both the items I wanted were not on display, but after asking I discovered they were locked away, and it was certainly necessary to ask! After some time looking around at the amazing array of stuff, I managed to get what I was after and leave. Fry's is a wonderful experience if you are in the right frame of mind.
What to pay: Cheaper than most around. The best deal!