I am in search of two Yamaha amps. I need either a pair of YPA-600's (2x50w/1x150 bridged) or a pair of YPA-1000's (4x50w/2x120 bridged). I would also consider the slightly newer (1992-ish) YPA-620 or YPA-1020. Must be in good working condition and decent cosmetic condition. Include a price with shipping to northern Michigan. Thanks.