Ikea has meatballs offer on wednesdays only- It is called 'Rollover Wednesdays'. It costs £1.50 for a small plate with 10 meatballs with chips/potatoes and gravy and lingonberry jam. It usually costs £3.25. So, it is less than half price!
I think this offer is valid with family card only. And with family card you can get free coffee, tea or hot chocolate too.
It is certainly in Cardiff Ikea and I am sure it is in all Ikeas- the offer was advertised on the 2010 catalogue.