Supermicro boards go great in Supermicro 4U cases. I'm using an X10DRH-C in a case that holds 36 X 3.5" drives with a SAS backplane. You can grab a CSE-847 for 350 plus tax and shipping on ebay.
A set of cheap rack rails attached to some 2x4's with a couple casters on the bottom and you have a rack you can stick in a closet and pull our when you need it.
The cheap rosewill cases are ok. But it you need to swap a drive (I have the 15 bay version that's about 100 bucks I used for my server to begin with and now use it for a router with only two drives) it's a pain to deal with. You have to pull the top, then remove screws to pull the cage for 5 drives, then pull the drive that you need to swap. It doesn't sound like a big deal til a drive goes bad, or one of the 120mm fans that cool the drives dies.
The Supermicro is the bottom one, the Rosewill is above it.
They also make wall brackets you can hang the chassis on and it can sit on a desk as well.