I swear by Old Navy dress pants, they're perfect for everyone. They have regular, long, and short lengths so that's going to save you a trip to the Alterations shop. Express also has nice pants, but at a higher price point (hold out for sale time).
Also, as Liz said, check out the sales racks at stores, you'd be surprised by how many wardrobe staples are on those racks. Just so you know, most sales racks are in the back of the stores so make a bee-line for them.
From what I've seen, Target has poorly made garments (their construction standards are low), so does K-Mart. If you can find a "cheap and cheerful" clothing chain in your area (i.e. H&M, Old Navy), you'd get better made garments there.
If you have friends who work in retail, ask them to keep an eye out for sales. Also, sign up for
newsletters from your favorite retailers so that they can inform you of upcoming sales.