sahm,
It's a very pricey area and 700k won't get you very far.
Have a look on myhome.ie around Ringsend/ Irishtown.
Lived lived for a few years and loved it.
Lack of Garden space a problem with kids though - that's why we moved further out of town but you're going to have to compromise on something if you want to live close to Ballsbridge.
I'd suggest looking further out of town - good bus routes along N11.