I've had very good luck using a little Sony ECM55-B lapel mic. It's designed to be a lavalier, and it's a very nice little condenser. They run about $250 new, and about $200 on Ebay. Clipped to the bottom of the sound hole, it is VASTLY superior to any of the sound hole pickups I've found. Barring investing in an L.R. Baggs with installation, I'd say this is a very good bet.