Peak travel/vacation season at a popular national park with limited accommodations is going to result in high rates.
When are you looking to stay?
Indian Park Campgrounds has tents/cabins for rates starting at $129, but I imagine they're fairly limited. When I booked similar accommodations near Denali, they filled about 6 months ahead of peak summer travel times.
Cedar Lodge also has less expensive rooms, but only for a few of the random dates I checked in June - $189.