How far is your commute?
I started commuting last year with an old rigid steel mtn bike that I upgraded to 9 speed. My commute is 12 miles each way. After a while I realized the lack of different hand and seating positions was taking it's toll for a ride that long, so I bought another old mtn bike and outfitted it with road bars. I used a Nitto Periscopa stem ($50), which got the flats of the bars slightly above seat level, while the drops are below. I used a Nitto Randonneur bar ($35) with Shimano bar end shifters ($100) and added Soma Cross Levers ($30) to the flats to add another set of brake handles for moving around in traffic, and I'm so glad I added those. But all in all, I bought the bike for $125 and am now at $1000, so you'll need to do some pricing to see if it's in your range for a bike that will spend a lot of time outside.
If you go to the Rivendell bike website (rivbike.com), and go to the section on stems, they give a good comparison of the available riser stems and how high each one will raise your bars.
You definitely give up some of the slow speed agility with drop bars since they are narrower, but there is a range of sizes.