Make sure you've completed the game at least once(on any difficulty).

Mission 3. Right at the beginning, work your way through the tunnel until you get to the first fight, kill the enemies. Backtrack to a wooden fence, break it, and Devil Trigger the object. Continue to combo it.

What takes maybe one minute to do gives you anywhere from 4000-5000 red orbs. Restart the mission, and redo it. Restarting will give you anywhere from 50-100 Proud souls as well.

VERY NIIIICE

To add to it, the same method, minus the enemies, can be done on Mission 7 as well.

If you bump up the difficulty, such as to Son of Sparda, you can get as many as 400 Proud Souls doing the Mission 3 version.

Granted, Proud Soul farming is better left to Bloody Palace, but you'll get an easy 5000 if you're looking to buy all of the Blue and Purple Orbs for health and Devil Trigger.

This helps a ton, but the Mission 7 one is the best because:
1.No enemies to deal with
and 2.Those eggs all around the 1st area are FULL of red orbs

I agree with Haranabi

VERY NICE

SWEET!! thanks Ekou, u rock:P

F'N SWEET THANK YOU SOO MUCH THIS WILL HELP SOO MUCH I NEED ALOT OF BLUE ORBS AND PURPLE CUZ IM STUCK ON 19 ON SON OF SPARDA!!!!!!!!!!!!!!!!!!!!!!!!![b][/b][i][/i][u][/u]

THANKS!!!!YOU ROCK!!!!!!!!!

thanks u helpd me out cuz i thought u couldent get orbs if u redid a mission u couldent get any orb u alredy got it will relly help (on last demon hunter mission with no gold orbs)