oops here is the New York one!

http://www.studyabroad.careers360.com/living-expenses-for-international-students

I know you mentioned some like Malta before so just a comparison for you

Malta

https://www.um.edu.mt/int-eu/international/livingcosts

this gives cost of living for different cities

http://www.numbeo.com/cost-of-living/country_result.jsp?country=Malta

London

https://www.imperial.ac.uk/study/pg/fees-and-funding/managing-your-money/living-costs/

and of course

Scotland Stirling cheapest place to live in UK for students

http://www.stir.ac.uk/undergraduate-study/financial-information/english,-welsh-and-northern-irish-students/livingcosts/

But Edinburgh is my personal fav!!

http://www.ed.ac.uk/studying/international/finance/cost-of-living

Galway is probably cheaper than Dublin

I have family member who moved to New York. Rent is extremely expensive - a single room apartment (500-600 square feet) can be easily > $1,500 / month.

Yes there are many Spanish speaking people living in Dublin and Ireland, and unless you share flats with non spanish speaking people it does not work to learn English:) I shared with Spanish speaking people when I lived there:) It is the same with all European cities really.I actually wonder if living in smaller towns would be better for some people as there are less people you have more opportunities to speak English. Or make sure you do not live or work with Spanish speaking people.

Dublin, New york is more expensive.
Dublin is full of Spanish, it's very difficult not to speak Spanish there