I purchase bag patterns from byannie.com for about $10, so it is a few dollars more than what I would expect.
I look at quilting and bag making as a hobby. I could buy a quilt at the big box store for far less than what it costs me to make - but that's no fun. When I start on a project I don't try to cost justify it or make money on it (I have a job for that). I spend what I can afford and enjoy the process.