My guppies and platies did breed but I kept them as there were health concerns, particularly with the platies- I did not wish to invade the shops with poor genetic stock, so am basically hanging onto to them and letting them live out their lives in my tank.
Porthole livebearers have bred- have sold at auction, swapped with other aquarists and given away, but lfs won't touch them as they are said to be boring in colour (so how come they sell black widow tetras- equally boring and less pleasant?).
Bristlies I have sold to lfs for store credit, but this may not last forever.
My rarer livebearers (ticos and tiger teddies are breeding) but as these are rare and a little sensitive I'll be selling them at auctions if I get too many, not taking them to the shop.
Am trying to spawn my peppered corys atm- if I get lucky, I may keep them or take them to the lfs for store credit.