Maine estate records have been uploaded by www.familysearch.org
, free to view. They are not indexed on the site, you must browse through the records books. But most of the books have name indexes at the beginning, so it's not a totally random process to look.
Coverage is not for all years for every County, and not all of the estate records books have been uploaded, but you might luck out.
Since Aroostook County was set off from Washington in the time period you are concerned with, if you don't find what you are looking for in Washington County, check out the Aroostook Co. material.
For some Counties, including Aroostook, there are also deeds on the same site. Unfortunately the earliest deeds for Aroostook have not been uploaded (yet?).