Right... proof strikes were evolving to a new standard between 1971 and 1972, and by 1973 they were near perfection. By 1974 they were pristine in quality due to the new sandblasting technology. The early Ike proofs were still acid dipped dies made the same way the Mint did it for a hundred years. By 1977 the proof Ikes were astounding in quality, thusly, a complete set of PF69 DCAM Ikes can be had for about $325 or so, compared to the same price or much more for a single circulation strike coin of high quality.