In case anyone is wondering how strong the shopkeeper is
Rough Estimate: Just for shits and giggles. Adding up all the items x31 (5 ppl x6 items each + 1 extra that he is still able to sell you) with the passives from just seraphs, muramana, deathcap, and cinderhulk:
You have:
508,013 Health 39,215 Armor 91,693 Ability Power 46,190 Attack Damage 16,709% Attack Speed 2,325% Lifesteal 210,800 Mana 24,490 Magic Resist 70,625% Base Health Regen 43,500% Base Mana Regen
This isn't without item passives and stuff like that.