update

There's also this that is interesting me: 


£12 from here

- 10DOF modules (three-axis gyroscope + triaxial accelerometer and three-axis magnetic field + atmospheric pressure) 
- Chip: MPU6050 + HMC5883L + BMP180 
- Power supply :3-5v 
- Means of communication: IIC communication protocol (fully compatible with 3-5v system containing LLC circuit) 
- Size: 2.2cm * 1.7cm

It would mean the possibility of having an artificial horizon 




Using the 5v booster idea, there's also this (more costly) possibilty of SimpleOSD:



SimpleOSD = £25 (plus import tax & postage) (£40)
Booster = £1
BMP180 = £2
= £43

More costly, but 4g in weight (as opposed to 8g & £13 of the Minimosd)