assuming you have all heirlooms unlocked on your account, all you have to do to make a 99.9% f2p bis toon (made up number):
level to 20, equip heirlooms, and buy vendor whites for your hand, wrist, and feet slots.
after that, there is a very steep diminishing returns in ilvl for your gold. you can make them on your main account, and the let them go vet when you unsub, or you can make them f2p on a starter edition of wow on the same battle.net.