You can find grafts in the following books:
Faiths of Eberron
Libris Mortis
Lords of Madness
Fiend Folio (incredibly expensive)
Magic of Eberron
Serpent Kingdoms
Races of the Dragon
Underdark
Faiths of Eberron, I think, would be your best bet for a cheap graft. The mighty arm (s) graft might be...