The 1927 Peace Dollar is a desirable coin for two reasons: it has the second lowest mintage of the series (one of only four dates with mintages below 1 million coins) and it is legitimately hard to find in nice condition. Overall, the 1927 Peace Dollar ranks as the third rarest of all the Peace Dollars in Mint State, behind only the 1928 and the 1934-S. In true Gem condition, it is the rarest of all the P-Mint Peace Dollars, beating out even the more celebrated 1928. Most certified examples fall into the MS-63 category, with significantly fewer appearing at the MS-64 level, followed by a big drop-off in MS-65 and only a handful in MS-66. Thus, the modern-day population reports have confirmed the "key" date status that the 1927 Peace Dollar has enjoyed for decades. In terms of eye appeal, this date usually comes with a good strike but a few too many bagmarks. The luster is often nice and strong, but mitigated by the afore-mentioned marks.
According to a notice in the June 1934 issue of The Numismatist (p. 416), collectors could still purchase Uncirculated 1927 Peace Dollars directly from the U.S. Treasury for "the face value of the coins and an amount sufficient to cover the mail charrges by first-class mail."