I'm curious. which SAS 2308 HBA are 20$ish.Yeah, that's a bit of a bummer, but in general, with SAS 2308 and 10gbe onboard, there's very little that needs to be added, generally speaking. 2308 based HBAs go for ~$20/ea and so do Mellanox ConnextX-3s. That's $40 just for these. And the heatsinks are probably $10 each. The motherboard is FREE!! . Just kidding. But, it uses standard PSUs, has IPMI, and no funky connectors.
I did buy a few to play around with.