I''ve been buying some nice errors as of late...wrong metals, some on wrong scrap, and other rather rare items...in order to see if I am paying within ballpark, to make fair offers, I use this final auction prices realized from heritage...I have found that just because a coin is listed at 12k..does not mean that's final...most of my new errors were offers made about 60-70% less asking price...it works, if you do the homework first..most sellers are happy to make a fair profit, and, move onto the next coin...this link has 11, 954 error coin records to see..besides, it's really cool to see the "Monster" errors...some are beyond mind-altering..and..very pricey...
==============
http://coins.ha.com/c/search-result...+790+231+330