Ok, she goes to school, (long story, but can't be avoided) but I know you lot are the best to ask, so apoligies in advance.
My nearly 5yo DD loves our local science museum, but of course we can't go as often as we would like, because of school getting in the way, plus I think that doing experiments at home would give her more chance to follow her own lines of enquiry and so on.
We have been working through a ks1 science workbook, but she wants more - eg she is currently interested in magnets but we have exhausted everything we can do with fridge magnets, with or without the workbook.
With it being her birthday soon, I would love to get her some equipment to use. She is only little now, but ideally it would last a while. We also have a 2yo DD who will be able to join in when she gets past the 'random acts of violence' stage 
So, where can I get hold of relatively cheap yet versitile science kit?