Wealth in The Last Remnant is measured in Gold. Shops throughout the game ask for this currency in exchange for items, and new recruits from guilds ask for a cash retainer when hired.
Probably the most important source for Gold is the capture and sale of monsters, closely followed by the sale of surplus equipment and components. Some quests and guild tasks reward substantial amounts of cash. Gold can also be found by Mr. Diggs at certain excavation points.
A trick used by people following the stat grinding playthrough to earn gold is to use Mr. Diggs, and harvest the diving point at the Vale of the Gods found near the entrance (b6 on the map provided by the wiki) for Rough Elven Stones, which could be sold for 300 gold each.
Another trick is to farm Bai Ze in Crookfen. His capture is worth 66,760g (28,800g on Xbox) and his spawn is immediately visible to the Southwest upon entering. Bai Ze is an easy fight and good for arts development. He also drops Blueprint 4. The best way to do this is to accept the quest The Cosmos Maiden, and when you talk to Sheryl in Crookfen, Bai Ze will 100% spawn. Run and fight him, and when you defeat him, you will always capture him. Use the exit nearest Sheryl (the one you use to unlock Melphina), say Yes when it asks to suspend the quest. Now you can keep forcibly spawning him, capturing him, and selling him.
XBOX 360 only: Hands down the best way to acquire gold is to farm the Bandit in Wyrmskeep with the zone/save/load trick. Best to find and fight Valkyrie for the guild quest first because when you zone back in the Bandit will be there 100% of the time, killing 2 Spiritlords with 1 stone. He nets 56k and you will reach 1,000,000 gold in less than 20 battles.
See Frequently Asked Questions for more gold tips.