If you pay someone to come to your home, you will have an employer-employee relationship and you will be required to register as an employer, remit P30's monthly and pay at least minimum wage per hour + employer's PRSI, pay statutory holidays, bank holidays etc.
The exception to this is an Au Pair who is seen as part of the family.
When I was looking in Dublin I was quoted €50 per day with meals included for one child in 2009 (for 3 days). I ended up going for the creche as I felt that it gave me more flexibility and some fall back in the event of a carer being sick or on holidays.