I’d consider at top $100. One should come with the Steam Machine right? It can’t be too expensive to manufacture if it’s coming with what should be a competitively priced PC

I have a terra master f4-425 plus. 3 NVME slots and 4 HDD slots. N150 CPU 16GB memory out the box

https://www.terra-master.com/products/f4-425-plus

F2-425 Plus has 2 HDD slots. 8GB memory out the box

https://www.terra-master.com/products/f2-425-plus

You could also go for the cheaper options like the non plus versions. Run whatever OS on it. I’m satisfied with the companies TOS