Here are some on line sources:
http://www.ireland-information.com/c...ticclipart.htm

http://www.ceolas.org/clipart.html

http://www.celtic-clipart.co.uk/

http://www.conjure.com/ICON/icons.html

http://www.celticlady.com/

http://www.joellessacredgrove.com/Clipart/