A miniature pig is a breed of pig developed for medical research but they are also used as pets. They became popular during the 80s; when full grown these little pigs should weigh between 35-65 pounds depending on their individual genetics.
The Vietnamese pig is the most common one.
Vietnamese pigs could be the best choice for you, they are the most common due to their size and they adapt well to new surroundings. Their size changes depending on what part of Vietnam they come from and the diet you feed them.