Figured I'd update to mention that I ended up purchasing an older model WD Passport drive, the WDBAAA5000ABK-NESN.
It was listed as working both here and on the gbatemp wiki (with multiple confirms there) and it was available as a re-certified drive direct from the WD store for $49.99. With tax and shipping it came up to $56.55. Only a 6 month warranty as a re-cert. drive, but it will either work or it won't.
So as soon as it arrives I should be set.