Buwizz has a special going.They have the Buwizz 1.0 €103,20 alone for €103.20, and as a combo deal they have that Buwizz with a Lego 42085 tracked racer (super esay build for kids) for €159.20. I believe they ship from Slovakia.
It's a bluetooth controller for power functions that can have a range over 80 feet outside. Also you can set more current that gets through, and really speed things up. There is a higher voltage below 11.5 votes vs that MAY be applied because it has an integrated lipo battery back. There's no way to do it accidnentally, you have to set the control on your tablet or phone to get that fealture consciously.
Here's a link from Sariel testing multiple configurations of this with Sbrick and with lego receivers/batteery backs. The don't do as well as the hype, but that are on a rough surface and don't have inserts, which apparently significant, as is the small size of the model.
Here's another with two of the tracked racers taking on obstetrical. He hurts himself with the motor choices, as he doesn't add big one that can REALLY handly the power, and he seams to have the rubber traction grommets only on the Buwizz kit. With the right motors for the right application, they do make a difference. However, you can tell from the video is more made for the large hulking sets than for this little ones, which it will help a little. He also shows how the app works. Instead of IR which is very short ranged at 18.5 ft, the Buwizz can go 735 feet (second video) from the Bluetooth on his android.