I can understand the frustration Cu, TheAirporter always seems to have just departed when you land, so it's an hour wait and then an hour and a half to get to Derry, traffic and weather permitting. Plus the hefty £25 return journey cost.
Never get a taxi from Derry Airport though, I always prebook with Foyle Delta... far cheaper. (But when you tell them you're in Liverpool, or Birmingham they do keep asking if you'll be on time!)