Envoy is a great hot tub and based on USD conversion, that is a fair price. Given that the Envoy has the lounger and captains chair and the 585 is no lounger, they really are different designs. Can you accommodate the Grandee instead of the Envoy, it’s a more comparable design?
I have no knowledge of Jacuzzi pricing, so can’t help there. I would wet test each and let that be your deciding factor if all else is equal to you.