Camping costs US$4 per person per day at any of the ranger stations; facilities include potable water and latrines. Sirena station has a covered platform, but other stations have no such luxuries. Remember to bring a flashlight or a headlamp, as the campsites are pitch black at night. Camping is not permitted in areas other than the ranger stations.
Try removing some filters. Alternatively, there are some nearby lodgings with availability below.