We do carry a variety of walkers. Most do not have a tray attached but usually have a bag to carry items as they are less likely to slide off. Trays can be added to several varieties of walker. I would recommend taking a look at the different types to see what you work best for the individual.
I'm not sure your better off calling and asking them. I would think if they don't have any in the store that they could order you one.
Thanks! Your answer is awaiting moderation.