Hello Lolabear, did you find a suitable yoga retreat. They can be expensive and perhaps even more expensive over the easter weekend.
I see open mind yoga are running a yoga retreat on the 20th to 22nd April which is 240 per person sharing. http://www.openmindyoga.ie/workshops/open-mind-yoga-yogaretreatsireland-retreat/
If there is a group of people going from the college yoga society you may be able to get a discount for a group booking.
Another option is to go to a weekend workshop in a centre in e.g in Galway Cork or Dublin and organise your own accomodation which may work out cheaper although it will lose the retreat feel.
As well Clare island yoga centre have the an open house option which is 80 per day sharing which would work out at 240 for 3 days but i think only includes one yoga class in the morning but the yoga room is open for you to practice in the evening. http://www.yogaretreats.ie/openhouse.htm
There are other options but are more expensive as far as I can see. Hope you are able to get sorted somewhere and enjoy the retreat.