Where can I find some nice dresses & blouses?

I really like 'professional' looking dresses and blouses, but still somewhat casual - if that makes any sense...

things like:

http://www.yuniti.com/photoalbum.php?user=4&img=34... (2nd from the left's top)

&

http://www.80spurple.com/shop/products/detail/5066... (but a little longer)

I've liked some things at forever21 in the past and Victoria's Secret, but everything always fits so big and VS is a wee bit expensive for my current budget. I'm relatively small; 5'4 and ~107 pounds. I'm 19 years old and I want to look classy/conservative, but still cute and sexy. I love styles from the 50's and 70's.

Do you know where I could find some dresses & blouses to match my style, that aren't too expensive or big? (under $40 an item preferably)