Hi jjj,
While I was visiting my son in Arizona (Feb 09) We came across a number of "meteorite retailers". Scattered in the vicinity of the famous Meteor Crater. The prices were around $100 US for a 200gm to several hundred for the Kilogram sizes.
At the Crater site itself there are pieces ranging from a few grams for $7 to larger ones for a few hundred. Much more reasonable prices for alien impact fragments.
Cheers Marty