I once had a conversation with Art Miller who designed the AR-18/AR-180. He told me in no uncertain terms that the best AR-180's were Howa's. Now how many folks know that is anybody's guess. I've had all three, Howa, ArmaLite, and Sterling and I'd say that a Howa is the best and the Sterling the worst. Prices on pre-ban AR-180's from what I've seen appear to vary widely. However in my opinion a nice, not abused, no box, no scope, and with a couple of real ArmaLite mags should go between $1100.00 and $1300.00. I have seen people asking stupidly large amounts of money for non-Sterling AR-180's but that doesn't mean they were sold.
Saying that a person can get two AR-15's for the price of one AR-180 is really non sequitar as you are comparing an original rifle no longer made (the new ArmaLite AR-180B rifle is not in the same collectors realm as an original) to one that is. Hell, "back in the day" I could have bought one SIG AMT for the price of two and one half AR-15's but guess which rifle is worth far more today-not the AR-15's.