There is a eight pages Tolkien's letter at e-bay:
http://cgi.ebay.com/JRR-Tolkien-Signe ... 837b&_trksid=p3286.c0.m14

item number: 140345639803
Seller info: chicagorarebooksengravings
Price: US $6,300.00
Dated:january 1947
signed on last page (there is one photo from every page)

About a correction of a paper.