I'd love to be able to buy and sell using Steem. I've posted about paying people for contributions to my guitar pick collection. If someone is selling music I like then I'd happily pay in Steem, if I have enough. It's more convenient than some of the other options, especially if paying internationally, and there are no fees.
You can easily transfer Steem to another user. Just need to include a message to say what it's for. Shops or other sites could generate codes to use there and I expect they could code something to handle it automatically. This is exciting technology.