Hi
We stayed at a great campsite in Eight Mile Plains - Brisbane Holiday Village -
www.brisbaneholiday.com.au or 0061733416133 -great cabins - clean, pool, shop/cafe and 30 mins from city. Very good as base when you arrive we wish we were still there!! Or there is a Big 4 camp/cabin site in Aspley which is north of the city
www.caravanvillage.com.au or 0061732634040 - Big 4 are usually very good - be cautious about jumping into rental the sites are probably better whilst you find your feet. Good Luck!
We paid $350 a week over the Christmas holidays but that included everything. We also have young children and they loved it there.
All the best
Heather&Mick