IMO MiniITX are a real PITA to build for on a budget. Most of the smaller components are sold at a premium because of their size.

I sell these things for a living and its exceptionally difficult to compete with pre-built ITX boards. Generally, I have to get a really great deal to come out on top vs some of the prefab models.

Because of that, unless you need something very specific and can’t find it elsewhere, I generally suggest that you do some research and find a nice prefab one for your needs. If you don’t mind spending the extra $, then building them is a hell of a lot of fun because you can customize them and you get exactly what you want, nothing extra.

Replacing the mini-rack with a completely 3D printable version will pretty significantly curtail the cost (between 1-300 euro because mini-racks are fucking expensive), so it might really be worth it if you can. Everything else is pretty trivial. Only thing you’ll have to make sure is you get a CPU and MB with enough PCIe lanes for you to expand to what you want. Specifically a PCIe X4 to 6 port SATA 3 host controller. The board only uses 4x lanes, but you’ll have to ensure that all 4 lanes are available or you’ll see reduced read/write speeds.