I'm debating whether to start buying whole gizzard-less and organ-less chickens and breaking them down myself into parts. I would only do this if it was more cost effective than buying the parts themselves. What would the proportions of the parts be to the whole on average? This is so I can do the math to see if this would be cost effective. I'd be looking for something like: breast: x%, y lbs wing: x%, y lbs thigh: x%, y lbs drumstick: x%, y lbs bone: x%, y lbs total: 100%, y lbs  where variables are replaced with actual values. 
Yes, when you switch the fan on, it is essentially a large air fryer. The only real difference is that air fryers have a smaller volume of air to heat, which makes them more efficient.  It's not all just marketing hype, these little fan ovens do have benefits over large fan ovens. Just a note here about oven nomenclature - what Americans call a "Convection oven" is called a "fan oven" here in the UK, and I suspect some other English speaking countries.  For us "convection" means without a fan, using natural convection currents, precisely the opposite of what it means in America. It's a total mystery to me as to why/how this has happened. 