Getting hold of runes and potions can be a difficult business. They are made with most effectiveness (and most cheaply) by members of the Alchemists, Artisans and Loremasters Guilds. Should you wish to equip yourself with a rune, a potion or a magical item, you should approach a member of one of these guilds with your request. They will probably give you a price and make the item for you. Fashioning runes requires the silver commodity, so you will be even more likely to receive a good price if you provide the silver for the alchemist to use. There will be times, though, that no Alchemist, Artisan or Loremaster is available or willing to use their talents to aid you. It is well advisable, therefore, to court friendship with at least some members of the creative guilds.
See HELP EQUIP for info on equipping legions with armaments and articles of war.