A good friend of mine (not saying who) got a spur of the moment clerkship interview while visiting her boyfriend. Of course she didn't bring a suit with her so she needs to find a suit, buy a pair of shoes, and research the judge all in 24 hours. I figured I'd help her out. These pieces are all from major national retailers so they should be relatively easy to find.
Banana Republic Petite Cotton Suit (209.00): Like me, my friend is petite and definitely does not have time for alterations
J Crew Isabel Dress (188.00): This is a great option if she packed a cardigan. A dress is infinitely more versatile than a suit if the right suit can't be found.
Theory Gabe Suit (660.00): I've never met a Theory suit that wasn't worth the investment. Buying a suit like this will last her a lifetime.
Lastly, Good Luck!