Maine is one of the slower states for postal history. Beyond a small hardcore group of collectors, there is little demand. As damning as this may seem, it represents an improvement over previous years. There is a lot of Maine material available, much of it is 19th Century, and it is one of the few states left where stampless covers are both cheap and ubiquitous. It is a very worthy state to collect.
Maine collectors are still scarce.
There is perhaps some small improvement, but supply still far outstrips demand. With the plethora of material available, there out to be more interest. Maine remains semi-permanently in the bottom ten states in terms of collector demand.