Hi: Looking to spend about $200-$250, I know this puts me into a used one mostly likely what brands should I look at. It is for a apartment setting room is 19x11x8. What would be a proper size?Thanks in advance

Paradigm 800F,Paradigm C600,Axiom QS8 v3,Paradigm DSP-3100 Sub,AVR Anthem MRX-740