Help with purchase of power conditioner

Hello, Ive recently been looking into buying a power conditioner but I don't know much about them. My budget is limited to 300 dollars new or used. My setup is as follows

Fronts: Paradigm mini monitors
Center: Paradigm studio cc
Surrounds: Paradigm ADP 350
Sub: Paradigm PW 2200
sony dvd player(budget player)
Onkyo Integra dtr-7 reciever
monster cable interconnects and speaker cables
Old magnavox 27" tv(next upgrade)

I've never had any experience with power conditioners and would really appreciate your input.