superjets are harder to find first of all and it simple as supply and demand with superjets.
if you find a good deal on one, act on it, as they dont last long. it took me 6 months to find mine locally and i lucked out. Its not uncommon to hear people driving 8 hours each way to go pick up a SJ.
you can find a square nose anywhere from 1K - 2K
a round nose anywhere from 2K-5K
in new england ( im from mass) SN usually sell for 1200-1800 on avg, depending on what is done to it.
check these out..
http://maine.craigslist.org/boa/671906428.html