I recommend to start from Amplify Thome and hp pot. U will need HP only on start in a critical situation. If you dont use it u can sell it after first shopping. Then proposes to buy soulstealer and boots of speed. Then Ionian boots and start collect the marelo Thome evils. If your team is not doing the best, or you think you need armor or magic resist proposing frozen heart or abbysal scepter, and later marelo. If everything goes nicely next item on the list is rabadon deathcap. If u will still play and u will have money u can buy rylais crystal scepter or shurelya reverie. But I doubt if ye had enough money. I believe the Soraka should have all the time wards. Only on start she dont need it. So much cash as you come down on Wards and I doubt you bought all of the items from list. Wards should be placed at random (with head :P)

Sry for my english and GL&HF