Last summer I moved into a new house with a steeply sloped front yard, so I figured it was time to buy a self-propelled lawn mower. After reading a few reviews online, I bought a 22-in. Toro Recycler with all-wheel drive (model 20353; toro.com). This thing is awesome! It climbs hills with ease and mulches grass into fine particles that feed my lawn. And the specially designed engine never needs oil changes–you just check and add oil as needed. This model costs about $400 at The Home Depot.