The closest town to Zion is Springdale, but if you don't want to pay an arm and a leg to stay outside the park, we recommend La Verkin (or Hurricane). Still close to the park (around 30-40 mins) and much more budget friendly with more amenities.

We stayed at a perfect little AirBnb in La Verkin, which had everything we needed and even a washer/dryer combo which allowed us to do our laundry.

Check this out if you'd like (not sponsored, we just loved it): https://www.airbnb.com/l/GNwi0kd1