Robot vacuums are already pretty great, but self-emptying models go one step further by removing the need to constantly empty the vacuum's built-in dust bin. The Shark IQ RV1001AE is one popular model that can charge itself and empty its own dust, and now you can get a refurbished model for just $269.99. By comparison, buying the same vacuum new from Amazon would cost you $458 right now.
The Shark IQ has most of the features you would expect in a high-end robot vacuum: floor mapping, scheduled cleanings, a self-cleaning brushroll that should keep pet/long hair from clogging, and a high-efficiency filter. It automatically returns to its charging station when the battery is low, and while it's charging, the station empties the dust bin into a larger container. Shark says the larger container holds "up to 30 days of dirt and debris."
The vacuum is available from Woot at the link below. Woot is owned by Amazon, so Amazon Prime members get free shipping.