I don't know about the too expensive bit (as I haven't compared) but there's artificialgrass.ie
They've a showroom just past Blanchardstown so you can see the differences in the different types.
Shell29 - how much artificial grass do you require ? Prices can vary a lot - if it's a small area, then something from a garden centre or even Aldi are currently selling it ().
Does depend on what you plan to use it for - just covering up a "rough area" or making sure you never have to get a mower out again