May Lotitio covered the frugality of sewing really well, I'll add some stuff about frugal patterning.
I buy Christmas paper after the holiday for making patterns. I look for designs that have a square grid to them, that lets me use it as giant graph paper. A design like that also lets you cut out pieces on the grain or with the nap by laying them out as you make them so the grid of the paper is how you want the grain. And the nap is right if the snowman is right side up (or whatever lets you orient it.) Some wrapping paper has a grid marked on the back, so when you are wrapping you can make straight cuts. That's the kind I like best, it's basically long pieces of graph paper! I'll take that type in any design, as it doesn't need gridded artwork to be useful. I hit a bunch of it a while back, bought several of the biggest rolls I could find.
I am a big fan of thrift stores, and always look for their fabric yardage, this area has a lot of quilters, and people's stashes show up when they move or die. Some pretty cloth! I also, though, look for cloth I don't like how it looks, but the feel is right for matching the fabrics I sew on. That gives me mock up fabric I don't mind cutting, that will drape the way my good cloth will. I snag cheap sheets for that too. Years ago I got 5 or 6 sets of top and bottom each, king sized, same awful print on all of them. I used that stuff for mock ups for a long time! I can't imagine having bought that for my bed, which they obviously had. Yuck! It was a horrible brown and yellow plaid, which gave it a great grid to work with!
I also check the thrift store fabric area for things like zippers, odd sewing machine parts, any other things I can use. My latest irritant that way is I have had it with any kind of plastic zippers. I am buying up all the metal toothed zippers I see. I'm also buying needle threaders, helps with my eyes as I get older. Also odd antique things.