There was a time when I paid for premium denim because I couldn't find jeans that fit me properly in lower-end stores. But times have changed, and now I find that the Gap and Loft make some great cuts that fit well (Madewell fit great too, to echo everyone here). It's worth trying on several sizes of the same pair to get a feel for your size, and go with the advice that I got years ago in a premium denim store: don't be afraid to go a little tight at first, since the very first day you wear them they will loosen up. If you put on a pair that has any looseness, particularly around the waist, right off the hanger, they will often become too loose after wear.
Some of the high end brands are really worth it, and some I have found are not. I think it's just trial and error. I have a pair of Hudson jeans that were expensive and yet I have to tug them into place after standing up. My favorite high-end jeans are AG. They really hold their shape and hold up well, no tugging.