I get by with a Shadow saddle replacement tranducer and a decent acoustic amp (Trace Elliott TA 50 + sometimes also a Laney LA65C hooked up if necessary) which gives a reasonable sound without feedback when properly EQed. But if you want really high quality sound you'll need to think in terms of a high quality PA (plenty of threads on these) plus a good microphone like an AKG C451 B (pricey). Also plenty of threads on microphones (which are very much a personal preference thing... as I can't afford the AKGs I use Shure SM 57s for miking instruments which are reasonably good).