I started the same way- buying for a specific project, buffering for errors and then saving the leftovers for scrappy quilts. Now, I still buy for the specific project, but look for fq or sale fabric to match stuff I have to make it go further.
I like the resources section here as people like to let us know of sales and I check them out. Have saved a lot of money that way too.
If I am purchasing something specifically, I always look for kids stuff since I do quilts for Project Linus and a yard of juvenile print fabric can go a long way in a baby quilt. Recently I was at Joann's and did this- found about 6 or 8 fabrics, bought a yard each at $2.00 a yard and now have a ton of ideas. Certainly easier than only getting 1 yard for $8.00.
I don't use household budget money for my fabric. This is my "hobby" and I don't burden my husband with my passion. I use money from my notary public commission- it's not much but it keeps me in fabric.
barb