three times more expensive than miners. twice as expensive as on vast.
Say huh?
Where did you get your info from?
Miners is comparing apples to oranges, but on Vast, how do you figure it is twice expensive as vast?! Or maybe I am reading what you said wrong.
Current rental rates on Vast:

Cheapest on Vast is $2.00 an hour for an 8 x 3090 rig.
That would be $2 x 24 hours = $48 a day. Now multiply that by 5 (40 / 8 = 5; to equal the 40 GPUs the op is advertising) $48 x 5 = $240 a day to rent 40 each 3090s on Vast.