most every place that sells kegs get green beer kegs for around that time. i would call ahead and place an order to make sure. i dont think they would keep a huge inventory just in case someone doesnt buy it.
Tigermart had them
Akasha had them
Kobe's but that is closed
Green beer? What the frick? Do they drink green beer in Ireland, NO. Green beer is for dumbasses that also only drink margaritas on May 5th (don't get me started on that stupid arse non-Mexican holiday).
Go buy a keg of Guinness you wanker.