We've never had plastic bases on our bins they sit on the soil. Vermin shouldn't be a problem so long as you don't compost cooked food or any animal produce.

No, the bin should sit directly on the soil so that worms can get in and out. I have never heard of a plastic base plate!

Thank you. That's great and saves me money!

I have the plastic base supplied with my compost bin and frankly its a pain the ridges in the bottom make it impossible to empty with a spade though the hatch and its very easy when 1/2 full for the bin to slide off it. I stopped using mine even though it very good at letting the worms and air in.