Car rentals at Dublin Airport

[Eamonnca1]

I've rented cars from Dublin Airport before, but they fleece you in there. I've heard about Shelbourne car rentals, based in Newry and Portadown. Apparently they'll leave the car for you at a hotel at the airport (walkable from the terminal) and you can pick up and drop off there with less hassle and at a fraction of the cost of the likes of Hertz and Europcar.

Has anyone used their service? Is it reliable?