The Eufy Omni C28 drops to $449.99 for Prime Big Deal Days, $350 off its $799.99 list price. The rest of Eufy's robot vacuum range is cut too, with savings of up to $430, most of them for Prime members only. Amazon's sale runs October 6 and 7, and according to Anker, the C28 keeps its $449.99 price until October 11.
Every model here is a mop-and-vac with a base station that empties the bin and cleans the mop for you. The more you spend, the more suction, cleverer navigation and extra hardware you get.
Eufy Omni C28: the one to get

We reviewed the Omni C28 earlier this year and called it premium features at a friendlier price. At $449.99, that's a much easier sell. Instead of spinning pads, it uses a self-cleaning roller mop, which keeps dirty water from being dragged around your kitchen.
- Eufy Omni C28: $449.99 (was $799.99, save $350) Amazon
- 15,000Pa suction
- HydroJet roller mop rinses itself nine times per second, according to Eufy
- DuoSpiral brush that Eufy says won't tangle with hair up to 11.8 inches long
- LiDAR navigation with no cameras on board
- Station empties into a 3L bag, which Eufy rates at 75 days, and hot-air dries the mop
Eufy Omni E25: more suction, more reach

- Eufy Omni E25: $569.96 (was $999.99, save $430) Amazon
The E25 steps up to 20,000Pa suction and adds Eufy's CornerRover arm, which reaches out to scrub along baseboards and into corners. We first covered it when Eufy announced it alongside the E28.
It costs about $120 more than the C28, so it makes sense if edges and corners are where your current vacuum gives up.
Eufy Omni S2: the flagship

The Omni S2 is $1,279.99 (was $1,599.99), and we called it the robot vacuum that finally nails the corners in our July review. Eufy quotes 30,000Pa suction and a station that washes the mop with 140°F water. It also makes electrolyzed water that, according to Eufy, kills 99.99% of bacteria on hard floors.
The verdict

For most homes, the Omni C28 at $449.99 is the pick: it has the roller mop and the full station without flagship pricing, and you get until October 11 to decide. Pick the E25 if you want better edge and corner cleaning, and the S2 if you want the best Eufy makes, but buy those on October 6 or 7, because their prices are Prime-only and end with the event.