Let me break a few things down for you.
I love to knit. It's like a meditation for me. I find it incredibly relaxing and I even get jittery on the days I don't get to knit (classic addiction!) But I'm by no means a fast knitter. I plod along at my own steady pace, which is fine because knitting was never intended to be a speed sport. People sometimes balk when they discover that my socks took a month to knit, or that sweater took 6 weeks. That's not 6 weeks of solid knitting mind you, but still.
Recently a co-worker admired my cropped cardigan saying he would like me to knit one for his sister. How much would I charge? I told him that the cost would depend greatly on choice of materials plus the time it took to knit the garment. He told me casually to let him know if it would be cost effective or if he could buy one cheaper at Target. I immediately told him to go to target. Let me tell you why.
The sweater I was wearing that day used 3 skeins of Pigeonroof Studios Cassiopeia in the colourway 'Juniper'. The yarn cost me $65AUD on sale. I bought 4 beautiful coconut shell buttons which cost a total of $12. Then I took a grand total of 42 days to knit the sweater. Now I didn't knit every day on the sweater so let's assume I knit for 21 days at an hour a day, so the finished product took an estimated 21 hours to knit. Now let's assume I want to be paid a tiny wage of $10 per hour for my time. That takes the finished cost of that sweater to a grand total of: $287AUD. Yep, that's right, math doesn't lie.
It's a pretty cute cardi though and sure, you could buy one a shitload cheaper in a store, but it would never be quite as awesome or infused with as much love (and sweat and tears) as a hand knit.