As promised, I've returned with a comprehensive look at where to find good, valuable tee shirts online. Of course, where to go depends heavily on what you want, so things are broken down into categories.
There's no reason to shell out big-bucks for basic solid-color tees (especially whites) that are almost always going to be worn underneath things. If you're going to wear a solid shirt as a standalone, yes, you might want to invest in something with excellent fit. In general, however, you're looking for value, vibrant colors, and comfortable fabric. To this end, cheaper department-type stores are often great (they have the volume to allow for lower prices), and often have sales when new brands of basic tee come along. You'll also be a little more sure of quality and durability.
Beware, non-basics here (design tee shirts) are less reliable in quality, not as good a value, and are much less likely to be uniquely worn. This is, of course, not really a factor for solid color shirts.
Creating Your Own:
If you want uniqueness, the easiest way to guarantee is to create your own design. You can do this by hand at home, but the artistic portion is often easier on the computer. Fortunately, there are a number of websites which allow you to upload designs to be made into shirts (or other garments). Many of these sites give you the option to keep your design private (ensuring yours is the only one), or to make it public (you make money off of it).
Obviously, with all the information, all the stores, and all the designs out on the internet, it's impossible to look through even a small percentage of the available material. Fortunately, you're not alone, and there are a number of websites which either distill the good information and good finds, or provide a community to discuss tee shirts.
Remember, especially with blogs, that you're only getting one person's point of view, and often this view is presented as obvious truth, but with no evidence! Don't be afraid to disagree or do your own research as well!
The Daily Tee
The T-Shirt Blog
Finding uniquely designed shirts often requires a bit more searching than the basics. Especially since people have different tastes, it's also hard to recommend places to look that will please everyone (or a majority, or even a minority!). This website provides a number of good jumping off places, but no real indication of what you'll find:
Other commonly known places which design shirts are (and there are many more out there):
Often, you're looking for a specific message or group to support with your tee shirt. These things are typically easier to find, given the specificity. For example, band tee shirts are usually very easy to find. Most of the time you can get them from the band's own webpage, and failing that, a google search of "xbandx tee shirt" is probably sufficient.
One website with a large number of band shirts is:
A good resource for sports team shirts (besides the websites of the teams themselves) is:
Even things you would assume to be very obscure can be tackled with a simple google search. Some examples:
Romeo and Juliet Shirt
Florida Everglades Shirts
School House Rock Shirt
Legends of the Hidden Temple Shirt
It's usually not that hard to find what a tee shirt, if you know ahead of time what you're looking for. If you're in search of a new wicked design, you may have to search a little longer, but the resources are out there. Unsatisfied with what's already out there? Take a stab at it yourself, people have made it amazingly easy to do nowadays! Enjoy and find your perfect shirt!