You'd have to buy the scales/runes/darts/pots. I'd take care of the rest. I used to sell fire capes and can provide plenty of proof. https://www.powerbot.org/community/topic/953445-razi_ftws-firecape-services-cheapest-on-powerbot/ <-- that's my firecape services.
I've completed the inferno multiple times now, and once on an 80 Defence account with book of law, ahrims, and pretty much trash gear. Got proof of everything including vids, the person I did it for, etc. I use a VPN and make sure that it's safe.
can sell an Inferno cape for 250M, using mostly my own gear. I've gotten it for my account and for my friend's account who doesn't have good stats (under 90 def, etc.) on a 150M gear budget in less than a day. Would prefer chatting on discord/skype. Can provide plenty of evidence.