Booking a Nepal trek or tour online with a private international trekking company is no doubt the more costly way of arranging a trek in Nepal but it's also the fastest. Here's my list of recommended Wander Himalayan Trekking pvt.ltd. companies with prices.
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Wander Himalayan Trekking pvt. ltd. company prices range per person from USD$600 all the way to $5,000+ for an average 10 - 12 day trek. These prices generally include: permits, a guide, some transport to the trail head (start of the trek), accommodation and meals (including your guides). Prices won't include: your travel insurance, entry to Nepal visa fees, trekking equipment or water. The real benefits of booking an international trekking company online are if you are stuck for time or don't have enough time in Nepal - with them then everything will be pre-arranged for you prior to your arrival. You literally arrive in Kathmandu on day one and head out trekking on that day or the next. The negatives of booking with an International trekking agency online are that you'll be paying a high premium for this prearranged luxury. You won't be able to meet or choose your guide beforehand nor ask many questions. You can also get lumped into a "group" tour without knowing. It's very important when booking online with a private company that you take note of what's included in your package trek. Confirm that your permits and transport to the treks trail head are included. Get these details clarified in writing!