There is no standard level of commission
Galleries often add on anywhere between 5% and 100% to the price as their commission, but commission on work sold through boutique shops or specialist stores may reach as much as 250% or more – making the final selling price two and a half times more than what the artist earns from the sale.
Art galleries struggles to sell art just as artists do
Galleries have to convince their clients that work by gallery artists is worth adding their collections. Many artists who show at galleries, including better known ones, not only struggle to maintain their relationships and continue getting shows, but also worry about making enough sales and enough money to survive.
Galleries don’t need more artists
Not only do the large majority of galleries already have more art and artists than they can handle, but they are also continually contacted by new artists looking for representation. What they really need is more buyers.
What’s the alternative then?
Social Media saturation, local events, art fairs, business breakfasts, art sale portals like ArtFinder etc, a good website, eBay, Amazon, Etsy. And have you tried picking up the phone and talking to people? What about people you know and the people they know? In business and in private. Galleries are but one place you can sell from. Think wider than that.