Weighing in at number 5 is Le Marche (MAHR-keh) region of Italy, in the center-east, along the coast of the Adriatic.
Now the reasoning behind this is that expats have been priced out of Tuscany first and Umbria second, so that they can compromise on Le Marche. I wouldn't do this. There's usually a reason things cost more, and Le Marche does not come close to most areas of Tuscany, or even Umbria. As leaving your country in retirement is an option and not a necessity, why compromise? I have been through Le Marche many times, with no compelling need to go back. It absolutely lacks the magic of its two neighbors. It may have the sea, which Umbria doesn't have, but the mid-Adriatic is polluted and the coast is undistinguished. I also disagree with their statement that it has the best fish cuisine in Italy. That's a tall order.
Retiring in Italy is not easy for the average person, or even the person of means. Much more research and careful consideration needs to be done, and facile tips such as this one are misleading at best.
(in the photo, Urbino, a must-see)