And it you get a breadmaking machine then I would argue that it's likely to be less environmentally friendly: a small oven is less efficient than a large one; plus the resources to make an electronic item vs centralised distribution.
I really don't see how making your own bread can be argued to be both environmentally friendly and cheaper, but am happy to be enlightened
But the point I'm most interested in discussing is the idea of maximizing the economic value of your time. In some cases this can be a useful heuristic, but the trick is knowing where and where not to apply it. If you were to apply that line of reasoning to every moment of your life, I doubt that the results would be satisfactory. Personally I'm more of a Gross National Happiness type. Of course, you're welcome to prove me wrong too :)
And if the energy to heat your oven comes from a clean source, you are good.
In most American places, it's illegal to build sufficiently dense housing to make it plausible for most people to live within walking or biking distance of their place of work (see Matt Yglesias's book The Rent is Too Damn High for more on this subject). While I agree with your point about not living 40 miles from your workplace, it's simply not possible in most of the U.S. for most people to commute by a means other than cars.
Perhaps road funding should only be paid out of gas and car taxes, and the federal government should stop subsidizing people's choices with other people's money, and then perhaps more people would choose to live closer to work.
Can you believe that in Germany you even get a tax rebate for living further away from work?
That's pretty funny since recently here in south eastern Canada we're being reamed up the ass by our current federal government for lack of jobs.
The government is demanding people find work even if it is an hour away which would be roughly 100km (62 miles).
Peddling to work takes longer. But I get exercise. The cave man diet takes quite a bit of effort. But it tastes damned good, is quality time with friends and family, keeps my money in the local economy (farmers markets vs big box grocers) and improves my health.
It just depends what a person chooses to optimize in their lives. When I was working more, it was not feasible to do the cave man diet or home remodeling.
For me it's actually faster. Due to heavy traffic at rush hours.