I bought the AVIC-Z110BT, which is hardware the exact same as the Z120BT. Only difference is a small software change (The whole globe spinning thing with audio mixing). I bought it from an Authorized Reseller off eBay (Refurb) for only $650. Must say it is the greatest purchase on a deck that I have made.
I still had to buy the Metra kit on top of that, which I found on a site for only $89 (I cannot remember the site but will attempt to find a link). Only thing I don't have at this point is steering wheel controls, but I have found some sites that post a DIY on how to make on for pretty cheap.