Pretty simple achievement though still involves a bit of luck, that being said here are some tips.

Don't buy anything at the shops.
Destroy all the clutter around each room to maximize your gold.
Some items can help you make this achievement easier: the "thieve's mask" doubles the value of each coin.

The "endlees pouch" gives you three coins per new room and finally the pirate sword gives you a gold coin f" gives you 3 coins per new room and finally the pirate sword gives you a gold coin for each enemy killed or destroyed item. if you're lucky enough to get both the mask and the sword then this achievement will be a lot easier.