Any one use those $140 90mm bodies off fleabay yet? If yes what results and other info did you find?

I bought a G-Plus on amazon 90mm LS style drive by cable. If this is what you are referring to. If you use quality sensors they are fine. If you are asking about the drive by wire sorry no clue.

looking at the drive by wire as a cheap upgrade for the 6.4 srt8 in my 1/2 ton 2011 truck

I have no answer on your cheap throttle body question, but I do have a question on increasing throttle body size.

What are the gains from increasing throttle body size?

Horsepower, torque, throttle response?

The 2010 Challenger SRT I just got has an Arrington 85mm throttle body on it.
It was done at the same time as a Comp Cam kit, Kooks headers and hi-flow cats

Well if it is the restriction in the intake then you can get more peak HP . Also since it should flow more even at part throttle then it should improve throttle response and MPG by making the same TQ at a lower throttle angle thereby keeping the trans from downshifting quite as frequently.

I guess I am gonna have to be the guineapig on this as I can't afford a name brand one right now.

In case anyone is still wondering about these, I tried one, looks very nice to hold in your hand, I was easily able to grind out the intake to fit butt it kept giving me all kind of codes about impossible throttle position and stuff. I suspect if you wanted to take one apart to adapt to a throttle cable it would be nice cheap way for that. I tried it on 3 different 2011 trucks and all were giving me the same codes, I also bought one for a 2014 but the customer who was going to let me try it out never showed up...

Yes i have used one of the cheapo ones from ebay. Works very well and no issues. the only thing in any of these units be it oem or aftermarket is two TPS sensors
and the stepper motor. The cheap one i have been using has a hall effect sensor for the two TPS , stock style uses a variable resistor type.