I have a Bunnings BBQ. its just a solid plate, 4 burner on a metal trolley. Nothing special. I got it when they were practically throwing out old stock (when my gf used to work there) for $50, about 4 years ago, and its still working like a charm.

I would get one from there, if i was looking. but only coz i still have access to staff discount, but that said, they would be cheaper I recon.

You could try Home Hardware, Makkit or something like that too?