as shop platform you could use something simple like ebay but you need to get very good discoverability of her works to find buyers - probably good solutions is

as shop platform you could use something simple like ebay but you need to get very good discoverability of her works to find buyers - probably good solutions is to use many social sites like Instagram, deviantart..., therefore you can build (or find) tools to automatize posting/managing images+descriptions to lot of places at same time.