Which Pre/Pro gives the biggest bang for the buck?

I would like to know which HT preamp/processor provides the most performance for the money in the used market? I'm not interested in HDMI. I'm only familiar with B&K products which I understand is the Low of the High End, like the B&K REF20($200) REF30($400) REF50($600). These to me represent good bargains/performance for money. I was wondering if there is a similiar or better deal out there to be had with comparable or better performance.