In my opinion - Gooster and antag are pretty useless - . They have links to several sites that don't even deliver to Ireland, and I found that some links don't even work, I also found wrong prices - out by as much as 50%. (and that was just a quick random check. They are just hoping for traffic and hope people click on ads.
Compareireland also a bit of a waste of time - as far as I can see it doesn't compare anything - it just provides links to a short list of suppliers of products with "prices from...." Some of the links are to shops that don't do online shopping (Peats and Argos) .
comparison.ie - I searched for Ipod touch - only came up with one supplier that delivered to Ireland (Komplett). Not much comparing going on there?
Street Prices - searched for a TV - it only came up with one price from a US site ! I dread to think what the delivery and duty charge would be if they even deliver to Ireland.
Pricefindr is very good - a non commercial site - and it is specific to Ireland with up to date prices.
Callcosts - also very good (government funded - so probably has a big budget) . The only thing is that it doesn't take into account all the various offers (like eircom free calls to meteor). I did notice another pricing error on it last last week and contacted them but I have had no response.