Manaslu is a restricted trekking region of Nepal, so you need to buy a special permit to trek there. Solo trekkers cannot get a permit individually, but they can join a trekking group to obtain one. Trekking to restricted areas is always more expensive than trekking to other areas. This is because you have to pay permit charges according to days and seasons. For the Manaslu Circuit Trek, the permit fee is USD 100 for the first 7 days during peak season (September to November) and USD 15 for each additional day. During low season (December to August), the permit fee is USD 75 for the first 7 days and USD 10 for each additional day.