One of the courses I had to take for one of my majors was a professional development course. We had a section on just interview attire alone. I, like you, am a young woman in need of a suit for an interview. Here's the breakdown of what I have learned as appropriate attire for an interview:
-My prof said go with a skirt suit, HOWEVER all my friends who interviewed for med and dent school said most people rarely wear a skirt. My sister is in charge of HR at a large investment banking firm and says pants are more appropriate in the business world at least.
-I will probably be going with a skirt if I can find a new suit that I like....but you just have to know how to sit in your suit. Practice sitting in your suit before your interviews to be sure it'll work out for you.
-your suit should be only the following colors: Black, Navy, brown, or Grey. Other colors are too flashy and pin stripes can be distracting.
-Look professional, but not boring. For instance, if you're a petite girl, don't go for a suit that your mother would wear..it could end up looking too big and swallow you. Find something that fits...not too tight...not too big.
-Shirts: go for a simple color as well. Don't go for a hot pink, once again, too flashy. Shirts don't necessarily have to be solid color...you can do stripes with the shirt, but just make sure everything matches.
-Shoes= REALLY important. do not wear peep toes. Interviewers don't want to see your nice little pedicure. Go for a medium-sized heel...something easy to walk in....don't go for flats though. Heels help you stand up straight. Make sure it covers your toe and your heel. Don't go for slingbacks. Shoes need to be neatly polished as well.
-Jewelry: Don't wear anything too wild. go for something simple. simple earrings, neckalace, watch, etc.
I hope this helps. If you want to check out The Limited, they have some decently priced, modern day suits. Just get advice from the sales people when you are shopping. They'll help you out to find something that looks professional enough.