Chenbro SR301 - 4 bay Mini-ITX NAS - Seller accepts $90 offers, free shipping

[Joelishness]

Ah, good point.
Also I found this which seems to answer my questions:

SATA or SAS controller card for SATA drives?

Things have changed in the past decade friend. (articles from 2010). The answer is you can use both SAS and Sata. You can use an expander to greatly increase the number of attached drives. You can add aDAS as well. They’re rock solid and stupid cheap. Makes cable management a breeze overall. Why limit yourself to just SATA TL;DR it’s almost all positives to use a SAS controller. Just make sure to use IT mode

So do I understand correctly that you can mix & match SAS and SATA drives?
If so, I can see how another benefit would be flexibility for whatever HDD deal comes around.