You can browse the exhibits at Třeboň Landscape & People Exhibition, a museum with a story of its own, during your trip to Trebon. While you're in the area, wander around the natural setting.
Sightseeing doesn't have to be expensive. You if want to get outdoors, try a visit to Svět Lake or make a stop at attractions like Trebon Exhibition House. Be certain a visit to Josef Susta monument is in your plans.