Well it really depends. I am going to sound nutty...but....
sometimes the fabric could be cheaper to buy it 1.00 off instead of the waiting for the sale. If a shop did not mark up prices and sold fabric for a dollar cheaper then they would seldom run sales, where as the shop that jack the price up can run a 2.00 sale on fabric and still cost more than the shop that charges a dollar less than SRP!
I am really bad, I never buy ANYRTHING (except food items that i HAVE to have RIGHT then and THERE!!!) unless it is on sale or clearance or I have a coupon!!! I also use comp ads at walmart! My husband use to think I was CRAZY and then he seen how much I saved and he will not go to walmart (its the only store we have around here without driving 25/30 miles) without checking the comp ads! I am a stay at home mom so I have the time to check the papers online and see who has what on sale, make a list and then go to walmart and compare prices sometimes you can get the walmart brand cheaper than you can get the name brand on sale and sometimes you can even get the name brand cheaper than the other stores have the name brand on sale!
I know this is clear as mudd....and long!