Makers are cheap. They are frugal and recycle and repurpose but overall they do not want to spend too much money. So why are the Arduino(tm) shields that connect to wifi so expensive?
Arduino wifi is in all rights nearly as powerful as an Arduino Due but costs a whopping $85. If you have a $30 Arduino, strapping this on is like putting a V8 in a baby Fiat.
Ok, time to turn to the 3rd parties. A history of boards show high prices also - the Sparkfun WiFly is $70.
Try China? Itead Studio's board is $60. The board at Seeed is $60 also.
And all these things are only 802.11 b/g and many require an open router. Hello??
What to do? Make one. I'm thinking the new Electric Imp at $30 and a interface shield at $20 and that's $50. And the Imp has a Cortex processor on-chip itself. I think a $30 solution would match the Arduino better but that seems like wishing.
The only other thought I have is some Arduino board with a USB host and can handle a cheap PC type USB wifi stick. I haven't seen anyone use such with a microcontroller, maybe someone will do that for the Due?