where is the cheapest place to buy print cartridges?

I bought some print cartridges for my printer 'Epson stylus cx3200' off the internet and out of four of them only 1 had ink in it, so I returned the other three, and the company sent me out replacements. Of the replacements one didn't work, and the other cartridge printed about 3 pages and ran out of ink.
can anyone suggest a place in town or one of the centres in Dublin to buy them that is relatively cheap?
thanks

Anything useful ?

Bring them to Cartridge World. Several branches nationwide. Sister runs ones the one in Drogheda. Basically they re-fill your old cartridges and are cheaper than buying a new cartridge.