Kona Dr dew - drop handlebars
About two years ago I converted my 2011 Dew to drop bars. I opted for Avid BB7 
Road mechanical disc brakes as they are compatible with short pull road brake levers. For shifters I chose to use bar ends because of their lower price and more simple design compared to STI levers. 

I ended up with a cost of about $325 for my 8 speed bar end shifters, Cane Creek short pull road levers, Avid BB7 Disc brakes, Salsa Cowbell 3 handlebars, and bar tape. I would expect to pay that much for the shifters alone if you opt for STI shifters as opposed to bar ends (the economical choice).