Ron Barczynski, 74, of Milwaukee -- who advertises the letter with a roadside sign proclaiming it to be a "letter from President Abraham Lincoln" -- said he wants $10,000 for the item, which he said was found in a picture frame he bought from a resale shop 40 years ago, the Milwaukee Journal Sentinel reported Wednesday.
"I want $10,000. It's a bargain," said Barczynski, who has been spending hours each day for several weeks sitting next to the sign in the hopes of attracting a buyer.
The letter is dated Sept. 20, 1864, and addressed to Maj. Gen. Philip Sheridan.
"Have just heard of your great victory. God bless you all, officers and men. Strongly inclined to come up and see you," reads the letter, which is signed "A. Lincoln."
Barczynski said he is suspicious of museums and appraisers, making it unlikely he will have the authenticity of the letter confirmed.