GDB mate i am not saying that your way is wrong. Its actually probably the best way. If you have the land you know what you eating. Probably why home grown fruit and veggies taste so much better.
The supermarket is basically the biggest part of cost of meat (or anything), they have those huge distribution centres with robots to build, those self checkout machines to install, electricity etc
The farmer is always the one that does the most work and usually makes the least profit, esp with intensive farming where feed, vets and even the stock is controlled by some very very big boys... those running the abattoirs.
Hence even if game meat was to reach a supermarket shelf it would probably cost more than beef/lamb.... as there would be a smaller market to buy the product so for supermarket to make their money they would increase the sale price.
Regarding my other comment. Mate it is your choice. I look at it as if i got sick for a few weeks or months i would have to pay someone to feed my animals, if so why not pay myself for my time (can be imaginary money if you prefer, but atleast then i know what my time is worth) and if i am doing that, i look at what's the minimum casual wage in Australia (as an example). Same way if my children do certain extra chores they know they can supliment their pocket money. this hopefully teaches them some important life lessons.