Two different 4 Bay NAS' on sale from TerraMaster. The F4-422 expires 11:35PM AEST, while the F4-210 expires 9:35PM AEST.
The F4-422 4 Bay NAS features an Intel Celeron J3455 quad-core CPU, a single 10GbE LAN port and two 1GbE LAN ports, 4GB RAM (upgradable) and 2 USB 3.0 ports on the rear. This NAS is the high end model from TerraMaster suitable for fast data transfer, Plex Transcoding, file storage, backups, Docker and more. It supports RAID, JBOD, Single and SSD cache. It's also possible to load another OS like Synology DSM or TrueNAS unofficially.
The F4-210 4 Bay NAS features a Realtek RTD1296 Quad-Core ARM CPU, 2GB RAM, 1GbE LAN and 2 USB 3.0 ports on the rear. This TerraMaster's entry level NAS and suitable for all the basics such as file storage and backups. It supports RAID, JBOD, Single and SSD cache.
Obviously the Synology D920+ for $689.70 from Newegg US is a good buy too with their excellent OS. It's always good to offer cheaper alternatives in my opinion.