I recently got a used Revo 3.3 in a trade. I've got it completely torn down, just parts and screws in bags, but before I put it back together I started looking at E-Revo conversions (I'm terrible with nitro). In my experience, conversions have always been expensive or a compromise, but I've heard that converting a Revo is easy and in many cases better than stock.
I don't want to spend more than $100 for this, as the truck runs great as is. My major concerns are cost, reliability, and where to put the batteries. I planned on selling the nitro stuff (engine, servos, tank) to fund the electronics, but I'm still weighing costs of the "extras". There are so many options for this conversion that it's almost overwhelming, but here are the options I'm looking at:
Option 1: ERevo chassis and tranny (I'm leaning to this as there is a spot for batteries)
Option 2: Emaxx/ERevo tranny on stock chassis (cheapest)
Option 3: RC Monster motor mount on stock tranny and chassis
Option 4: Aftermarket all the way! (GMaxx, etc.)