It is largely auto-generated from a set of Ruby scripts that fetch individual CafePress shop pages, parse out item details, and aggregate the data by product type. (No, it does not do that on every page hit; the scripts are run by hand when a shop is added or products change.)
CafePress makes it quite easy to set up a free store; all you really need is an idea and some decent graphics. The free sites, of course, have assorted limitations on the variety of images and products. There appears to be no limit on the number of free shops one has, so assigning one shop per graphic is a workable way to provide a range of products. Having a central site like this makes it easier to present what's available in one place.
CafePress charges a base price for each item, which they grab on each sale. A shop owner is free to charge whatever he or she cares (presumably more than what CafePress will charge the shop owner on each sale).
The items at Ruby Stuff have been marked up, on average, $2.00 each. (If you poke around CafePress a bit it is easy to find out what things cost and what what markups people apply; the Ruby Stuff markup is at the medium level.)
I hope people enjoy the offerings and find something they like. If you have a suggestion for a Ruby item, or have any questions, please let me know. And if you have any doubts about buying stuff from RubyStuff, consider this:
The buzz on the 'Net is that RubyStuff is the Ruby stuff shop of choice for developers of Web 2.0. And wearing a T-shirt from RubyStuff, or drinking an ordinary beverage from a RubyStuff mug, will make you 11 times more productive.
ruby DOT shop AT gmail DOT com