Good news: A reasonably affordable 1931-S Lincoln Cent on that Internet Auction Community, seller has 100% feedback rating of over 2000, shipping is a little high but not ridiculous. Bad news: Large fingerprint on reverse. My first thought was to just pass it by; there were, after all, 78 31-S's listed when I searched. But before I make that my "final answer," is there a cure for fingerprints that doesn't diminish the value of the coin? I have always assumed that there was not, but you know what happens when you assume.
First thoughts are often best thoughts. Acetone will frequently take care of a new fingerprint, but I've never heard of a do-it-yourself method for removing fingerprints which have set, and altered the surface of the coin; other than a thorough whizzing.
I say go for it. Sometimes grading services, as I have heard & seen, overlook the fingerprint if the coin is problem free otherwise.
I would pass--it is pretty easy to find a nice 1931-S cent in MS.... I have used Acetone to remove fingerprints and they went away...some totaly and some came back later on down the road but all of the coins have spots and such now that was left by the acetone. So they are damaged more than with the fingerprints IMHO. Speedy