On average, it costs €257 per week to stay in student accommodation in Dublin. The average price for Shared rooms is €210 per week, for Ensuites it is €255 per week, and for Studios it is €325 per week. The actual price will depend on the location, facilities and amenities offered by the accommodation as well as how recently it was built or refurbished. You can browse all options here .
Many properties allow you to pay for accommodation in installments rather than in a single lump sum payment. However, they will usually require you to have guarantor (a resident of Ireland between the age of 18 and 75 who will be able to pay your rent).
Yes, many student properties in Dublin allow for dual occupancy of their rooms (e.g. for couples, best friends, siblings). Some properties offer this option absolutely for free, others charge a little extra. When browsing student rooms on Campusboard watch out for the 'Dual occupancy' label which will explain the terms for that room.