I never really thought about it before, but did you look on EBay? They have everything else on earth there. Fortunately for me there are a couple places around home that buy and sell workout equipment.
EVEN COMMERCIAL GRADE USED SMITHS WILL BE TOO PRICEY. i would go to newyorkbarbells.com and click on the smith machine link. i believe that the one that runs on rollers is about 400.00 and the linear bearing (the one i would recommend) is about 700.00. do not be fooled by the price , they are pretty decent machines. btw hippie i see that a while ago you pm'ed me and some how i missed it. if you want pm me again...sorry about that.
Try the Yahoo search engine under "used gym equipment". A new commercial smith would cost $1500-2000. If he can afford it, spend 800-1k and he won't regret it b/c it'll last forever.
if anyone knows the where abouts of old nautilus equipment like the shit viator and mentzer trianed on then please pm me as the stuff jones designed back then was the shit