Thanks I thought it might have been from a shirt but 'The Dolphins' emblem was never on any of the kit as far as I know.
Sounds like it may be worth checking back on ebay every now and then, I can't find any badges similar to your avatar at the moment but at least it seems theres a few around.
Superphil could you tell me what the picture in your avatar is from? I've been watching out for some Dolphins memorabilia on ebay but nothing has come up yet.