What is that movie where these kids wish they had a new mum or something? And they go to some weird market where they can buy one but they only get three coins to use... I think oh and there's another movie where this maniken comes alive... and becomes their mum or something?

The first movie you're thinking of is "Trading Mom" where 3 kids decide they want to trade their mom for a new & cooler one. They realize though that the new moms they pick out aren't all they seem to be, and that no-one can replace your real mom! The second one might be "A Mom for Christmas" with Olivia Newton-John. She plays a mannequin who comes to life after a little girl sees her and wishes for a new mom. Hope this helps! :)