Did you try Big W for maternity jeans? Not sure what size they go down to as I'm a 14 but they have some for around $30 at the moment. Nothing fancy but they looked OK.

I've just started using the bonds belly bands (not sure if that's the correct name but they come in a two pack, one white one blue). They are a godsend.

Just noticed you are in Pakenham. There's a place in Hallam called Mollies Maternity that has cheap maternity jeans - I think all of them are under $50 from memory - again don't know what sizes they have but it might be worth a phone call. Just google their name. They had heaps of small stuff but might not be size 8.