What makes knitting and crocheting affordable?

What makes knitting and crocheting affordable? How do I define affordable?

 
If I choose to make my sweaters and accessories and only count the cost of the tools and yarn, I'm not getting a complete picture of how much I'm spending for each item. What part of my budget do I take these items from? My clothes budget? My hobby budget? Entertainment? General household?

 It would seem logical to take clothing made from a hobby from the clothes portion of my budget, but what about the time I spend doing these things? If I take the money from the hobby portion of my budget, I get a better idea of the complete picture. If I take the budget from the entertainment portion, it's an even better picture of my total budget for spending.

 If I take a small percentage, say 15%, from my clothes budget for the clothes I make, I still have money for clothes that I need immediately. If I take another small percentage, say 25% from the hobby budget for the hobby aspect, I still have money left for more yarn and tools. Tools get depreciated which means I can spread the hooks and needles and other notions costs across the years I do this hobby. If I take another small portion, 15%, from the general household part of my budget, I can count it because it can be used to enhance my work appearance. It can also count from the household budget, if it's a gift. Mostly, I count it from the entertainment budget. Knitting and crocheting are entertaining for me. I can still get movies, go places, and do other fun things as they appear. There is still money from my husband's portion of the entertainment budget for us to do things together. I can watch movies, listen to music or audio books, converse with friends, walk while knitting or crocheting.

 Now the best thing about this plan is that if I follow this, I have a bunch of money in my budget for yarns. This is because knitting and crocheting take time. If I use fine yarns with fine hooks or needles, I have a bunch of hours of entertainment for my investment. The larger the project, the more hours I have for entertainment and the less money per hour of entertainment I spend. If I use fat yarn and big needles or hooks, my investment goes down a bit, but these are usually accessories rather than a sweater or skirt. Super bulky yarn doesn't make a good fashion choice for most people.