I second sewing if you are interested in fashion. It isn't exactly "cheap" in that it usually is no cheaper or slightly more expensive to make an item than buy a similar item, in addition to the time.
However, it is cheap in the sense of time of enjoyment/ frustration/ learning per dollar.
If I buy the fabric for a dress, (say, 3 yards) at 40% off with a coupon, it is probably $20 Thread, zipper, new needle, other notions, $5. $25 If it is a complex enough dress, It could take me up to 15hours of cutting, basting, adjusting, sewing, finishing, ironing, shopping, selecting a pattern, etc. That's $1.66 an hour.
Knitting can be the same, especially if you knit with small yarn- socks, mittens, gloves, hats.