I am the queen of sale shopping. I feel like such an ass when I pay full price for most things, just because I had to have it then and there. With most chain stores though, it seems that the prices are set so that they can mark it down substantially and still make a profit.
My rule of thumb is that if I see it at Gap, wait a few weeks, then it will be on the sale rack. Usually in my size too. The one advantage to being an 8/10 as opposed to something smaller. They usually don't sell out of my size because its not as common
Beware of Gap outlet stores, though. Its the previous year's merchandise. For example, I was at the one in Foley, AL this summer and saw lots of clothes that I bought LAST YEAR for sale. Same with winter stuff. Although, if its nondescript stuff like tees and sweats, its mad cheap and worth it.
Anyone ever gotten anything from Old Navy for $1.99? I've gotten two skirts that way, just because they were marked XS, but were not sized correctly. They had gotten overlooked so much they were priced down. Good for me though, I actually tried them on and they fit