barth_bh:
Sorry post is old, but ESP8266 make it all and cost is only 3$
Can you post a link to an ESP8266 shield for $3? Best price I found was $6USD: http://www.aliexpress.com/item/Free-Shipping-Smart-Electronics-ESP-12E-WeMos-D1-WiFi-uno-based-ESP8266-shield-for-arduino-Compatible/32653235884.html.
Edit:
After looking at the pictures more closely this turns out not to be a shield as the description states, but rather an ESP8266 based board in an Uno form factor. I guess it would be useful for compatibility with shields(assuming they work with 3.3V) but you can get two NodeMCU boards for the same price without the idiotic Arduino header spacing.
I did find a couple of ESP8266 shields:
http://www.aliexpress.com/item/Free-Shipping-New-Version-WiFi-Development-Board-Module-Based-Web-Sever-ESP8266-Hot-Selling/32608666678.html
The headers are a bit strange but the documentation is better than you would normally expect for this sort of thing: Introduction | ESP8266-Based Serial WiFi Shield for Arduino----User Manual
http://www.ebay.com/itm/191821165193
Seems a bit overpriced and the documentation is practically non-existent(the website on the silkscreen has been shut down for a while).