I have never collected them, but have always been fond of the IoM coins. Might want to add the cast 1709 coins on to your list also, they are believed to be the first coins known to have been issued on the IoM.
BTW the Triskeles is a much older symbol, and it predates being used on the IoM coinage by about 2000 years:

SICILY, Syracuse. Reign of Agathokles, c. 317-289 BC. AR 8-Litrai (6.85g). Head of Athena wearing Corinthian helmet left / Pegasus flying left, triskeles below. SNG ANS 684. A fascinating aspect of this coin is it's remarkable similarity to the well known Corinthian Staters from the same era. Like their modern descendants, ancient minters knew a good thing when they saw on it, and if they could improve upon the design all the better. What distinguishes this piece from the Corinth issues is the presence of the Sicilian "Triskeles" on the reverse of the piece under Pegasus. This "Triskeles" is symbolic of the island of Sicily.
Back on track here, I would suggest haunting Spink.com, www.baldwins.sh, coinsofbritain.com. Right now I do not recall seeing stuff from the islands on their sites but it is only a matter of time. I haunt those sites looking for Scottish booty of course, and occasionally something good comes