eh, i just found a shield that can provide some external RAM, so is the RAM's problem solved?
That only works with the Mega boards based on the ATmega1280/2560. Not the Uno which is based on the ATmega328. So no, the RAM issue hasn't been solved.
Plus you still have to write the drivers for the Arduino to support the USB Dongle device. Without documentation from the manufacturer, that might be difficult.
so, what we're trying to do is to repeat create the wheel.
if we want to cost down, the best idea is use other wireless solutions.
the cost seems cheaper than wifi, i think the restrict maybe bigger than wifi.
think about the Smart homes, thousands of sensors and switch, use wifi maybe a better choice.
anyway, i found a datasheet of the RTL8188CUS http://wenku.baidu.com/view/6eadaf215901020207409c77.html
i always looking forward to low price wifi module.