RE: Cheapest T-Rex setup
Cheap is not necessarily poor performance, it just depends on what you do with it.
If you're not flying hard 3d with it then HS56 all around and the Align gyro are just fine. I use this and it is stable, it does fly inverted and it can even flip and such. It may not be as aggressive and strong as "digital" all around with a 401 gyro, but hey, you get what you pay for.
I would also not suggest to have your kids try yours... ;-) especially not with an expensive setup. Despite what peoply think, digital servos can break too!
Ron