I personally have the Canon 100 mm f/2.8L IS and it is a fantastic lens, but also pricey (used with an APS-C sensor). You should consider the Canon EF-S 60 mm f/2.8 Macro - about $40% the price of the 100 mm at 400 US (B+H). Gets very good reviews too.
http://www.the-digital-picture.com/R...ns-Review.aspx
http://www.fredmiranda.com/reviews/s...7&cat=2&page=2