Euro Car parts sell them for a fiver. tell them you want a water temperature sender.
the senders they have now are a different head, they are a wee plug rather than spade - so they dont snap as easily. all you need to do is break the black plastic protector of the red/green wire this will expose the wee plug that will slip onto the new sender plug
also, in the mean time id swap the red/yellow wire (dash temp gauge) over with the red/green wire. and just use the oil temp as an indication of temp.
ISV is more important than your dash temperature gauge, and they both use the same type of sender