Looks OK, and Buffalo is a known name in the market.
Anything you get will have RAID, so best to also buy spare drives for when one of them fucks up. Never RAID 0. Either RAID 1 or better yet, RAID 5 if your unit can do it.
See this for an explanation (https://www.wundertech.net/what-is-the-best-raid-for-nas-devices/)
Also, RAID is not backup it's just disk redundancy. It pays to also backup to a single high capacity disk in case of major oopsies.
Good luck.