you can't buy much for $2,000 to move a crowd, assuming your looking for QUALITY sound)

12 sub, doesn't cut it for 500 people, maybe for 200 people

i'd say a single powered 18" would be better than 2-12"
but that right there is at least $1,000 (new QSC 18")

i think you'd have to spend at least $3,000 if not more to ROCK out 500 people with QUALITY sound