There is a cheap way, it just depends on whether or not you want to manually shift the trans all the time.
The cheap way involves a Transgo valvebody reprogramming kit. You modify the valvebody as per the instructions, and drill the case for a vacuum line that is ported to intake manifold vacuum. That vacuum line goes to a vacuum modulator that is part of the kit that replaces the Electronic shift valve inside the trans, and is fitted to the valvebody. The only electronics required after the reprogramming kit is installed is a on/off switch to engage O/D, and lock up the converter.
Now I'm not gonna name any names here, but some people just plod along w/o looking into stuff (Nick), and go pouring money out on the ground (Nick), before checking out all of their options. Those same people, (Nick) then travel all over Ethiopia, (Iowa) Looking for obscure, hard to find parts like 164 tooth flexplate, and midplate dividers (Nick) instead of just cutting and welding the starter into the correct position on the plate, or doing away w/ the divider plate altogether, and just using the little Autozone starter locator rings that could be bought for 10 bucks. Then those same people (Nick) start a thread stating that some other people (me), lead them down the wrong path based on partial information that I supposedly provided. all while coming around at the end and deciding that they, (Nick) in fact LOVE the parts that they, (Nick) bought based on my, (Michael L. Matkosky,...resident expert on all things that have anything to do with 4R70W related) advice.