DESS, where and how to obtain the prices

I am living in Belgium and finished a setup with 3x MP2 3000 and 4x Pylontech US5000. Our energy supplier is Luminus, currently with a variable price, mid-december I can change to a dynamic contract.

Everything is working fine and the next step is setting up DESS in trade mode.

I managed to finish the wizard in VRM and I understand that the buying price and selling price can be manipulated.

The only (very important) thing is where VRM obtains the prices. Somehow it gets prices.
Can anybody shine a light on it?