The thing about the added color is that it is very difficult to know when it was added. Theoretically, if the color was added close to the time of issuing, and done well, that would be okay; but for me, if the hand-coloring was added significantly later, that would hurt the value of the item.
I agree with Barry. Some people prefer them with hand-color, some do not. Some people also prefer the prints to be part of a full, intact issue of Harper's, while others only want the sheet with the print so that they can display it more easily.
Harper's prints are pretty common, and yours does not look to be in great shape--from a quick look, I see staining and tears along the perimeter. To me, it would be worth anywhere from $30 to $70. If you check eBay regularly, these are the type of prices you will see. But here are a couple of decent comparable sales outside of eBay for you:
http://www.auctionscc.com/archive/20...century/421/#a
http://www.rarenewspapers.com/view/1...rection%3Ddesc (this newspaper dealer has one for $125 and one in lesser condition for $64).
I have no idea what happened here, and would not consider this a viable comparative sale:
http://monthly.scpauctions.com/LotDe...px?lotid=16741
It is a great image, as are many of the wood engravings from Harper's and Leslie's, but it is not worth a lot of money.
Hope this helps,
Charles