The internet is full of breeders selling teacup and mirco-mini pigs, but many of their claims are false. Jake Swearingen has dug into the teacup pig scam on Modern Farmer:
“Teacup pigs” (also sometimes sold as “micro pigs,” “pocket pigs” and “Juliana pigs”) are a marketing scam reaching back at least two decades, if not more. It works like this: Breeders put up listings for “teacup pigs,” promising to sell petite porkers a pig that’ll stay permanently tiny. Buyers then pay anywhere from $750 to over $3,500 for their teacup pig. The buyer then watches as that tiny pig becomes a larger adolescent pig, then a very large, very non-teacup-sized hog.
There are, of course, some breeders are acting more ethically, either declining to promise the adult size or offering more realistic estimates of adult weight, which can be as little as 30 pounds but is more likely to reach to 70 or even sometimes 100.
But in a sense, simply calling a pig "teacup" sized is misleading. Veterinary Patty Khuly writes that the term makes her cringe. "Just as with dogs, the word 'teacup' purports to describe the size of a pig for marketing purposes alone. It is not a distinct species or breed of pig. It’s just a pig who’s been bred to be smaller than most."
Perhaps most disturbingly, some sellers advise new owners to only feed the piglets a quarter cup of food per day, essentially leading owners to stunt their pet's growth by starvation.