Go with a PA type system, big bullet proof woofers and a horn tweeter, sound reinforcement gear:
These speakers, "quality you get what you pay for", and well who knows how "good" they'd sound, but they're big loud and cheap.
onlyfactorydirect | eBay
they even have powered units with built in amp, so heck you could power them off any signal source.
New Pro Audio PA DJ 600 Watt Powered Speaker PP1203A1 | eBay