I don't know about a flower pot, but most can be grown in a larger container, say half a whiskey barrel. I have a couple that I grow in Earthboxes.
Most dwarf trees get 6-8 feet high, but can be pruned shorter, if need be, to about 4-5 feet high. Typically, you can find them at your local nursery, which is your best bet because they will carry species that do well in your climate.
Otherwise, many seed catalogues carry them. My favourite is Raintree Nursery.
Citrus does VERY well in containers. I have also had success with the shrubby stuff, like grapes and pomegranates.