But Donegal’s largest town still has the lowest overall costs nationally for students living away from home, it is claimed. AdvertisementThe comparison website switcher.ie singled out Letterkenny in its newly published yearly Student Cost of Living study. Compared to Letterkenny’s annual cost of €14,065, the cost in Sligo is €14,205 and Dublin costs €19,990. “Lower accommodation costs give students in Letterkenny and Sligo a valuable head start. She added: “Letterkenny continues to lead the affordability table, helped by the lowest accommodation costs in the country.