This is my formula as well.

I am a newbie to with very, very little stash but I am buying some on sale and at thrift stores .

WOW I never realized there was a method to our madness. :P I shop sales use coupons -also church rummage sales 2nd hand stores and watch the newspaper for estate/yd sales,and before you know it your in competition with JoAnns.My DH use to say I did not need any more fabric or shoes but he always made sure I had cash in my pocket in case I was attacked by either of my fetishes. ;-)

I have a friend tell me once that if I should find a material I absolutely love, to buy at least 3 yards even if I don't know what I'll do with it right away.

I've been getting a lot of materials on clearance at Walmart. Not everything is marked down. Have fun building up your stash!!

check craigslist for garage sales. search fabric sewing or material and you can sometin=mes find someone saleing some of their stash for a good deal.

If you see some that you like and can afford to, buy several yards of it at a time. Usually that will be enough for using it in any project. If you really love it 3-4 yards are better. Enjoy shopping. :)

When I started I was told to buy fat quarters to build my stash. 900 fat quarters later, I now find I need way more for borders, sashing, backing, etc. (Note I am learning to piece backs, etc)
I now buy
- 3 yards if I think it is good for borders or sashing
- 1 yard if it is too good of a deal to pass up but I have no idea what I might use it for

I originally built my stash from sewing dresses for grandkids. And if I really like a print I will normally buy a minimum of 3 yards. Anything I make I try to buy a little extra.