Fairyhouse racevourse on the Navan road used to do them every Sunday. Havn't been in a while so double check. Was a decent one too stalls and all the things you expect at a car boot sale - cheap razors, washing powder, electrical goods and new release cinema films on DVD!
Thanks everyone, have found one in Inchicore which is every Saturday and Sunday and one in Kilcullen on 3rd of May. I might try the Inchicore one and depending on how it goes, Kilkenny if it's good.
Yea they do be regular enough in Caragh alright at least every bank holiday weekend. Iv never been though so I cant speak for quality. As for Fairyhouse I dont think you can put a car in and its very hard to get a stall, they wont just let you in as a once off, it's kind of a regular thing that your there each week.