There should be a transformation master in every world i worked out some prices and what kind of transformations you can KEEP in a page in you spell book.
wc transformations cost 5000 gold
kt transformations cost 15000 gold
mb transformations cost 30000 gold
ms transformations cost 60000 gold
ds transformations cost 120000 gold
cl transformations cost 150000 gold
ice transformations: ice beetle,ice serpent,evil snowman,collossus,ice giant and ice angel
fire transformations: fire cat,fire elf,sun bird,phoneix,helephant and efreet holding his lamp as wand
storm transformation: storm snake,storm bats,kraken,stormzilla,triton in a bubble and stormlord
death transformations: ghoul,banshee,vampire,skeleton pirate,wraith and scarecrow
life transformations: imp,leperchuan,unicorn,searph,centaur
This is pointless. The transformations we currently have are enough, and the Polymorphs are somewhat linked to transformations (you look different and things change about you). More importantly, Some of these would take a while to script(scripting is giving a computer a command using a special language). Basically, No. sorry if it offends you.