Upload & Sell: On
Start at $1,000,000 and work your way down.
Give yourself five years to build up a decent portfolio.
Why? Because light, weather, seasons, all change. To be in the right place at the right time is not just a computation of time and space, it's also being lucky. The beautiful pictures in snow, or fog, they don't just happen every day.
Everyone thinks their snapshots are wonderful. Have you printed anything large? Like 2 foot by 3 foot? Sharpness, color, contrast, exposure all become very noticeable. Have you built up a portfolio of quality images?
Although people say equipment is not important, to some extent it is. Particularly when printing large.
Are their galleries in the area? Go study what others are doing and charging. Often a big part of the final selling price is the framing and presentation. It all contributes to the bottom line net profit.
I live in a resort town and see galleries come and go. The fact is, most photographers have diversified into writing books, magazine articles, leading photo tours, and doing whatever it takes to make it work. If you are just doing this part time to supplement other income, then having a handful of shots may work. But still, getting 15-20 great images takes a lot of work.
So after all that, since you asked I see 8.5x11" prints for $25, 11x14" prints going for $35, I've seen large framed prints of 36"x48" framed and originally priced at $1,200 being discounted to $600. I also see boatloads of those prints just sitting in bins. What does your friend want, as far as his cut?
I don't want to sound cynical, but successful landscape photographers are probably as rare as professional sports figures, or like any field very few finally rise to the top and succeed long term. In the end, it's practice, practice, shoot, shoot, and study. And, as they say "being there." And the more you immerse yourself into landscape photography, the more critical you will become of your work. You may, in a year, look at what you once thought was great with a more critical eye and realize it's crap... And vice-versa with some you thought were nothing.
Actually though, this is primarily an amateur board, for serious hobbyists to show their work. Although there are professionals that come and go, their appearances are kind of rare. There is another board "Pro Digital Forum" that might be able to tell you more.