Roomba
You seem to be under the impression that UK buyers can only get Roomba from America. That's nonsense. I've had my Roomba for about six months and bought him from a UK website, in pounds, with a proper British plug. No adapters here.
Also, although I do live in a one-level, hard-floored flat with no rugs or obstacles, I love my Roomba. He trundles off his base station at 2.30 every afternoon and hoovers up for me, then puts himself away for charging. He gets right under the sofa and tables, and I've yet to see him go far wrong. Daily hoovering with absolutely zero effort is more than worth £250 to me.