I’ve had a look, not purchased, but watched a lot of review videos and I’d recommend you to do the same as no one here is going to have really tried all the different models available.
Unfortunately, the price does seem to correlate with the quality and performance and the most expensive auto vacuums cost in the £300 region. They also will never be as powerful as a traditional upright, can’t do stairs and of course you still have to empty them and take them up and down the stairs to do the different floors of your house. But yh, the price is the biggest reason I’ve not gotten one myself.