Bundoran is 40 minutes from both Sligo and Donegal Airport. It is also close to a variety of other airports mentioned below

Donegal Airport:
The Irish Airline Aerarran fly from Dublin & the UK to Donegal airport www.aerarran.com

Sligo Airport:
The Irish Airline Aerarran fly from Dublin & the UK to Donegal airport www.aerarran.com

Knock Airport, Mayo
Knock airport in Mayo, an hour an a half south from Bundoran has flight to Dublin, the UK and further afield into Austria, Spain and the rest of Europe. The following arilines fly to it
www.ryanair.com
www.bmibaby.com
www.xl.com
www.aerarran.com

City of Derry
The city of Derry airport, an hour and a half drive into Northern Ireland, has flights to London, Dublin, Liverpool, Glasgow, Spain through:
www.ryanair.com
www.ba.com
www.cityofderryairport.com

From Dublin, 
Fly into Dublin and drive 3 and a half hours north west and you are in Bundoran

Car Hire

Avis operate at all the above local airports. International companies also.