I thrid the NY & Company - affordable, work-appropriate clothing. I feel your pain in the shirt department. I finally realized that I should buy button-ups in the size that fits my boobs and take them to a tailor to bring the waist in to be fitted. If we can bitch to the shorties to go to the tailor, I guess the juggs girls need to go, too!
I also think Target has some great, affordble stuff. Especially in the tops arena - lots of twin sets and nice "dressy" t-shirts.
Valkyrie - I love the idea about a tank under a cardigan! I never thought of that and I'm always hiking the undershirt part up so the creepy guys at work aren't looking down my top as they stand over me!