I've occasionally considered setting up a t-shirt site for indie gaming merchandise generally and then inviting all the various small studios and game creators to submit designs (or let me make designs based on their IPs) and then share profits.
Is Attract Mode doing this, or something different (I mean I know they sell not just t-shirts, but I'm not sure how they choose what they sell)?
The main problem I have with CafePress is how expensive they are. Also there is a big difference between a nice shirt and a cheap shirt in fit and feel, it's kind of not worth it in my opinion to sell cheap shirts. Basically I feel like it's almost worth it to do order fulfillment yourself -- how many t-shirts do you think you'll sell?
I've done a run of just 25 shirts at a local screen printer (this is in Seattle), American Apparel with one color and a glow-in-the-dark glaze (they did the photoshop work to make that screen), and it was about $9 a shirt. The shirts themselves were $5 for that size of an order. With shipping that's about $11 for a very nice shirt.
A friend and old housemate of mine frequently would do runs of shirts in our house (printing in the basement and his room), usually about 400-600 shirts. He would charge around $500-700 dollars for this I believe, get them done in couple of days usually. With the cost of the shirts added at that size of an order it probably was a few grand total.
Anyway my point is that while CafePress is convenient, they're stupidly expensive and the product may not be what you want in the end.