Another concept is satisfaction. There is no pride in wearing a scarf from the gap (well, I suppose for some people, who derive self-worth from brand names, there is) but I'd say that being able to respond to the question "Where did you get that?" with "I made it." is probably worth some money in itself.
My wife crochets while she's watching TV. So that would be lost time otherwise. Suddenly that lost time becomes a $10/hr job.
We've been giving home-made presents a lot lately, and while at times I feel a little "cheap" because we're giving gifts of things we'd make for free because we enjoy doing it, that's all erased when someone says "You should sell this stuff!". Seeing the afghans my wife makes balled up in the corner of the couch when we visit relatives makes us proud. You can't buy that at the gap for any amount of money.