Isle Of Man 1977 Half Penny

So, I was going through a large lot of junk copper I bought a few months back and found 4 1977 Isle of Man half pennies I just Googled the name and came up with this:

http://en.numista.com/catalogue/pieces6388.html

Now, one of the coins only had the signature PM on the obverse but 3 of them have a BM on the obverse and the reverse. Numista calls this variety "rare" but what exactly does "rare" mean in relation to this? And what is the value, the 3 pieces are in varying degrees of uncirculated. I know Isle of Man coins are in low (no?) demand and so even a "rare" variety would likely not sell for much, but what would be the estimated value and where would be the best place to sell it? (sell it on ebay, any well-known Isle of Man coin dealers that would pay a premium for it?)

Thanks!