Quick Answer
You can see Saturn's rings with any telescope of 60mm aperture or larger at about 75× magnification. The Sky-Watcher Heritage 130P tabletop Dobsonian offers the best Saturn views under $300 — its 130mm parabolic mirror reveals the rings, the Cassini Division (the dark gap within the rings), and subtle cloud bands on the planet. For GoTo convenience, the Celestron NexStar 4SE or 5SE provide excellent Saturn views with automatic object tracking. For the best visual experience, an 8-inch (200mm) Dobsonian like the Sky-Watcher Classic 200P shows Saturn's cloud bands, the Cassini Division clearly, and up to six of Saturn's moons on a dark night.