I found an easy way to get this achievement.
In the Prologue there's a level called The Fluffy Menace where I usually get a lot of the Blue, Yellow and Purple currencies. I simply replayed that level over and over using Inferna until I gathered enough currency, then simply quit and load the game back up with your preferred character and buy what you need until you have all 4 statues complete.
All your currency carries over between all 4 characters, so there's no need to keep replaying the level with each, Inferna seems to be the strongest so I stuck with her.
Hope this helps.