GunBroker places the Ruger Mk III's in the $250-469 range. Not many are threaded and about eight are fluted, but no premium seems to be being paid for either feature. It would seem that the your two Rugers are falling right into the mid-price range and are probably a good buy if in good condition.
Edmund Burke: The people never give up their liberties but under some delusion. 1784 speech. Taken from Founding Fathers Notes
"In a State of Nature, it is true, that a Man of superior Force may beat or rob me; but then it is true, that I am at full Liberty to defend myself, or make Reprisal by Surprize or by Cunning, or by any other way in which I may be superior to him. But in Political Society ... if I attempt to avenge myself, the whole Force of that Society is ready to complete my Ruin."
-Edmund Burke, A Vindication of Natural Society (1757), original spelling and punctuation.