Real geek t-shirts can be purchased at Zazzle or Future Shop or Best Buy. One can also check any generic t-shirt store , to find shirts that would appeal to your brother- in-law.
Geek Squad shares the in-house uniform supplier that Best Buy does. Uniforms can only be ordered by registered Best Buy Managers and Assistant Managers using a network application only available within the Best Buy stores. You can find Geek Squad shirts on eBay sometimes.
There is quite a selection over at www.thinkgeek.com. There are some unique finds on there like shirts that light up and comic book hero hoodies. You might also be able to find some good deals on bundles of shirts at Amazon.
Shop online.
Doctor Who tee shirts can be purchased online at eBay, Amazon and Listia. They might also have them on the shows website or your local Hastings, or Best Buy.
Most basic retailers sell fun, geeky shirts. Target and Hot Topic are two stores that always have a good supply of "geek culture" shirts, although finding a more science-oriented gift might be difficult. The Gap is another good choice, although it might have a smaller selection of geek shirts than Target and especially Hot Topic.
I would not say there is a geek store but the closest thing would be Best Buy. They have the Geek Squad service, and they have lots of gadgets large and small suitable for any true geek.
buy it online i think
There are many different online shops and sites which are tailored to sell geek stuff. Geek stuff can be easily bought at online comic stores or electronics stores.
One can find more information about Woolrich shirts online at the Woolrich website. They not only give full detail about their shirts, but they also offer great deals and discounts if you buy online.
You can find various t-shirts for babies on shopping sites such as eBay. You can also check the websites of clothing stores as well as the sites of big box retailers such as Walmart and Target.
online, at your local mall, or at an aero store