Watch out, most of those protien bars are packed with sugar.
I like the Think Thin bars:
http://www.thinkproducts.com/thin-bars.php
They are high in protein, taste good and are sugar free (sugar alcohol only).
OH and as for where - I get them at Wegmans. They come in well under $2 each.
They are around $16 for 10 at Amazon.
http://www.amazon.com/thinkThin-Chun.../dp/B000CRHQN0
The PB is really good, as is the Chocolate Fudge.