Here's $2.85 with lots of feedback: http://www.aliexpress.com/item/new-Wireless-module-CH340-NodeMcu-V3-Lua-WIFI-Internet-of-Things-development-board-based-ESP8

Here's $2.85 with lots of feedback: http://www.aliexpress.com/item/new-Wireless-module-CH340-NodeMcu-V3-Lua-WIFI-Internet-of-Things-development-board-based-ESP8266/32520574539.html http://www.aliexpress.com/item/new-Wireless-module-CH340-Nod... Personally I've bought from this one: http://www.aliexpress.com/item/NodeMcu-Lua-WIFI-development-board-based-on-the-ESP8266-Internet-of-things/32338129505.html http://www.aliexpress.com/item/NodeMcu-Lua-WIFI-development-... So far tested 3 units and they work without any problem, packaging was also very good. I don't see any cheaper than those currently, but once you have everything tested, if you want to cut the cost you can always just use esp8266 directly which goes for $1.8