Art Gallery SW does not get involved with the commissioning of art from the artists on the website. However, there is no reason why you can’t approach any artist on the website and see if they would be interested in doing something special for you. Many would be very happy to do commissions. We don’t have anything to do with the terms you agree with them, they are entirely between you and the artist.
You should decide first how much money you want to spend, what you want and when you want it done by. As many of the artists are local you might want to go and visit them and have a chat. Typically, you will pay a bit in advance and the rest in stages.