I want to get some kind of robotic and/or rover kit for my older brother. I had in mind a sensor and/or remote-controlled multi-wheeled thing that can navigate around and do something cool -- potentially leading the way toward quad-copter sort of stuff. I'm looking for something in the $100-200 range, preferably Arduino controlled. Ideally, hacking should be completely optional... that is, it should do something interesting without having to write much if any code. Soldering and assembly is fine, but it should be relatively complete. If they have to go sourcing stepper controllers and gears it'll probably never get built.
He has two kids, one not quite a pre-teen, the other a bit younger. None of them are currently into programming or electronics, but they're all really bright and he certainly has an engineering mentality, so opportunity for that sort of thing is a plus. The older kid especially I suspect will grow into DIY if he's introduced to it.
I've seen lots of stuff like this around, but my focus has always been on other things so I don't really know where to start. Any recommendations while I Google?
Look into OWI kits, as well as kits by Tamiya. For instance, there's the OWI-536 All Terrain Robot kit; there's also the Tamiya 70104/70107 Dozer kits. Neither are programmable, but could be made into a robot with appropriate hardware (Arduino, sensors, motor controllers, etc).
OWI/Elenco also sell programmable robot kits, but not much in the way of what you are looking for. You might also look at the Robot Shop for kits:http://www.robotshop.com/robot-kits.html
...though they may or may not be out of your budget; there is this kit, though - which isn't out of your budget, and kinda fits the bill:http://www.robotshop.com/dfrobotshop-rover-tracked-robot-basic-kit-3.html
Finally - you could always go the Lego Mindstorms NXT route (just slightly above your budget)...