A number of Chinese built Arduino boards fitted with a cheaper USB chip, the CH340G are appearing on eBay. I purchased one recently for £2.83 post paid and it arrived from China in less than two weeks. So what are they like? The USB chip needs a driver, but I had no problem finding the driver on the Internet. Installing the driver was easy, just running the provided exe file.
The board looks like a UNO to the Arduino IDE, so once the driver is installed just select the right port and connect it as a UNO. So how does it differ? To me this board is an improvement on the official board, there are two extra analog pins, the USB connector is a standard mobile phone type USB connector. This removes the problem of shields shorting out on the standard USB connector. There is a group of 2 x 4 pins where Tx and Rx as well as SDA and SCL are brought out (together with 5v and Gnd). The board I purchased also had a strip of pins to solder onto the board to take advantage of these additional features. A useful feature is the ability to solder male pins alongside the usual female pins.
In my view this board improves on the official board and at this price it’s unbeatable.