Gyros/Accelerometers? Compass?

[kresty]

I'm headed toward a balancing head for my BB-8, which pretty much means that I'll need something to know where the head is.  I'm expecting to use some sort of gyro/accelerometer thing, but I don't know anything about them.  I'm starting to do some research, but I'm hoping that someone has "expert" advice.

I expect to use sensor to determine when the head is "tipping" and then have it do the appropriate thing to drive back up on top of the dome.  So that should be not unlike a gyrocopter keeping itself level.

Also considering if I want something in the hamster to keep it from climbing the ball too much.

Also wondering if maybe I want to consider a compass in the hamster so that the operator and the hamster can have a frame of reference.  Even if the hamster rotates, it'll know how far it rotated, so it can map the inputs accordingly.  May not be worth the effort.

Anyway, I found a GY-87 @ Banggood.com that seems cheap.  ($9).  Is that worth looking at?  Are there different modules/chips? 

One factor is I'm uncertain of my controller at the moment.  Either a Raspberry Pi 2 or Arduino most likely.

[kresty]

Eagerly awaiting suggestions.... Found this 6050 as well: http://www.banggood.com/6DOF-MPU-6050-3-...80862.html $3

[kresty]

Savage said he'd post something, but I ended up picking up these: MPU-6050 Gyros - 5 of them for $12
http://www.banggood.com/5Pcs-6DOF-MPU-60...59259.html
and these HMC5883L compass sensor, 5 for $6.

So 5 for the price of 2 of the other things (~$10 each), miss the pressure, but I'm not flying so probably don't need that. And I figure I don't need the compass on both the head and the body, so I'll have spares for other projects or if I fry them as I've done to other boards. Also maybe w/o pressure it'll use less power, though that's probably negligible and a wash.