Munchkin kittens can be found at shelters and cat rescue groups for a small adoption fee, and sometimes for free. A breed so specific is difficult to pinpoint at a certain shelter, so it may take some time and a watchful eye until one shows up in the system.
Although somewhat rare, Munchkin kittens do occasionally end up at shelters or feline rescue groups. The initial adoptive families may realize that they aren't suited for the amount of care or money that goes into a small kitten and forfeit them, or they may have been taken in off the street. This is the best chance to adopt this kind of kitten at little to no cost.