Use the following trick after you have obtained Catalogues 2 and 3 to get easy Gold. Go to the unmarked island on the southeast corner of the world map and buy some Eternias from the owner of Catalogue 2 for 30,000 Gold. Exit out and talk to the owner again selling him the Eternias through Catalogue 3 for 750,000 Gold. Keep repeating this process until you get the amount of Gold you want.
To get this secret character you must first get Nephi after visiting the entrance of Isopolis. Then return to the Corridor of Clouds and go back to the entrance of Abraxus' Tower. Instead of entering the Tower go to the right and examine the door and Nephi will unlock it. Then find the purple person and examine him and after a brief scene you will have Doll in your party. Remember to scour the workshop to get useful armour for your party.
The Sigil armaments can be found at the following locations.
Sigil Blade: At the Draken Mansion during the Sub-Quest with Kairu.
Sigil Helm: Buy for 100,000 Gold at or near the clothier in Tradefair.
Sigil Necklace: At the Cytherian Bridge on the way to Tradefair.
Sigil Armor: Go to the northeast area of the map by airship. Then enter the city and fight in the tournament and you will receive it after defeating several fighters.
Sigil Armlet: At the far southeast of the desert in the Black Send sub-area (if walking from Polamaze this location is due east). Find the stairs that lead into a secret area and defeat the monster there.