I would avoid mechanical drives at this point, as the SSD's aren't that much more expensive and you avoid having to worry about moving parts.

The KingSpec I believe has been proven to work on the 30GB Zune. I haven't tested a 30GB, but my 80/120 Zune's also worked with the SuperTalent which, when in stock, is usually a bit cheaper than the KingSpec:

https://www.amazon.com/Super-Talent-DuraDrive-128GB-FEU128MD1X/dp/B00TPLKQLS/ref=sr_1_fkmr2_1?s=electronics&ie=UTF8&qid=1515452473

I attempted a 256GB ZIF btw some months back but I believe these Zunes have a 128GB limitation. Only tested the 80/120 btw, not the 30.