Prior to the current massive shortage and "gouge pricing", well over 40 Mhash on ETH was EASY to achieve for well under $600 using a pair of RX 470/480/570/580 cards or a pair of GTX 1060 cards.
I think you could also get there NOW via 3 x GTX 1050 - which are still in wide fairly good supply and NOT getting price gouged at all - for under $500 and possibly close to $400.

 Tradeoff is that the rig density is lower.

Seems like a bit of a crapshoot with those cards. $629 seems like a lot for 3 months warranty, no backplate, and temps seem high for running at 100% fan.

I'd rather pay the same price for a similar hash rate and a 3 year warranty with an almost guaranteed ability to sell the card on the used market.

As I know, Bitnand offers the P104-100 mining rig with 9 GPU. The design looks very cool.
But 1 P104-100 with 629$, I think it's quite expensive. They gives spec. is 40 Mh/s ETH mining, but in a demonstration image, the reported hashrate is 31.8 Mh/s, it's quite strange.