IMHO, its quite expensive given that its an older model even if you'll get it brand new.
I have the higher model SCPT570 which I got bundled with my PV80. The difference with 170 is the ipod dock, floorstanding front speakers and higher speaker wattage. Its better than most HTIB but I wont even shell out 7500K for the 870 nowadays.
Try looking in the Marketplace. There just might be a cheaper option to suit your needs.