imo thats not a particularly good deal. you can buy 3 aduino promini on ebay/aliexpress populated, programmed, and ready to go, for the price of one of those. in fact a "bare-duino", as shown below, with industry standard power rails on each pin for servos, motors, sensors etc can be built for a dollar or two (see the led poking its little nose out?).
using this minimalist philosophy a complete robot can be built for less, similar to the $50 one, complete with motors and sensors. thats around $8 with off-the-shelf, not junk box, parts too. and i managed to place with it in a local m&m sorting contest.