I worked in the art world for years. First as a studio assistant, then as an art prep for large galleries, then eventually I ran my own art fabrication business with a few employees.

A good gallery--emphasis on good--does a lot more then simply sell art to the highest bidder. They strategically place artists into 'important' collections, work with museum curators to bring the artists into a more critical narrative, get the artist into group shows and fairs internationally to contextualize the artist in a current scene or trend, collude with art critiques and magazines, and generally help to promote the artist's career over the long term.

All of this sounds somewhat silly outside the art world, but you have to remember that this is a very particular industry based around historicizing high-brow cultural production. When a good collector buys a painting, they are doing more then just buying a physical object they like. They are throwing their own clout behind the artist and saying "I think what this person is doing is important and I stand behind it."

All of this is done with the intention of increasing the profile of the artist which benefits--each in their own way--gallery, the artist, and the collector over the long term.

As far as the sales split between gallery and artist, standard split is roughly 50% with some variance around material expenses and whatnot.

Note, everything I am saying is the sort of ideal story and there are a lot of bad actors in the business. In reality I find the art world rather gross and the premises it is built upon to be deeply flawed.

I don't see the relevance of app stores to the sale of artworks...?

Auctions take a small cut because they are resellers of art. The artist doesn't get paid when a work sells at auction, the previous owner does.

Art is usually sold by galleries, and the standard cut there is 50%. On top of that, artist and gallery often share discounts, so a work that is sold for a 20% discount means the artist will only see 40% of the total price. For artists, this will be a pleasant surprise rather than a steep expense.

We spent a considerable amount of time deciding this split, and consulted with many of our artists on what they felt was fair.

While the customer facing portion of the website appears like a more traditional marketplace, our artist facing website contains tools for artists, and we do more than just list their art, we help them get better at selling, help them promote and market their art, and we provide support wherever needed.

We are artist centric first and foremost, and always heavily consider and consult our artists point of view.

I live in a village in NM filled with artists. I continue to be surprised to hear the stories of how their galleries take 40% or more. I'm even more suprised that they are happy with this, but the general rule seems to be that they are happy because the gallery they use now increased their annual revenue by more than 100%.

Early on, when Art in Res was just an idea, we played with a model where we took zero commission and monetized other ways. But, when we talked to our artists about it, they were skeptical and would ask "but how will you make money?"

I hear you that, when looked at in a certain light, it might seems high – but we work closely with our artists and they seem to all like that our incentives are aligned. Plus, we do our best to use that 30% in ways that benefit them, e.g. by guaranteeing that they get paid if someone absconds with their work without paying it all the way off.

The relevant comparator is SaatchiArt online, which takes a 35% cut.