Log replacement can have a wide range of cost. It really depends on what type of log home you have, the size of the logs, and how many logs actually need to be replaced. As you can imagine, these can all affect the cost drastically. Usually a contractor can get you some rough costs if you have photos and a rough idea of how many logs or how many feet of replacement will be needed.
I would recommend contacting American Log Restoration, Inc. and sending them some photos and information about your issues as well as where the home is located. They can get you some rough costs from there and then could plan a site visit if you are interested in getting the project fixed. You can email office@logrepair.com or call 231-258-0382. Their website is www.logrepair.com.