approach distributors to see if they could sell you the next best/better servo at the SG-90 price.
That has crossed my little mind 
I need to find out if there IS a better but still low-cost servo..
There are some plotted here: http://homepages.paradise.net.nz/bhabbott/Servo.html
I buy about 1200 to 1500 servos per school year. I think we paid a little less than $2 last year. I need to keep the overall cost of a kit like THIS down.. there's a lot of stuff in there.. Hmmm...
I already know that to run the DC motor in the kit with PWM on the power FET that the user HAS to use an external supply. It's just that the servos plug right into the 3-pin connectors on the RoboRED and it LOOKS so easy... 9V 1A wall warts are cheap. One big school system has gone to "MakerSpace" kits where we put 8 kits worth of parts in larger Akro-mils drawers, and some 9V 1A supplies go in that packaging.
Main thing is it needs to work for the teachers and students without mysterious failures...
Well. We'll see how THIS works out...
Thanks!