Winner gets both "slots" — the big mouth and small character.
Small character can be pony or some lookalike only. (earth ponies, pegasi, unicorns, alicorns, bat ponies, changelings, kirins) Other races are negotiable if the winning bid ends up at $80 or above. Big mouth can be changed only in terms of colour and probably other small things, but has to retain the shape, which can be changed for something around the autobuy.
Extra details and/or extra changes will require a markup, typically $10-20.
Primary payment options are Patreon and Boosty. Others are discussable.