Far Cry 3 Classic Edition
43 Achievements
1,000
20-25h
Xbox One
Xbox Series
Money to Burn
Spend $5000 at the shop.
20
30.75%
How to unlock the Money to Burn achievement in Far Cry 3 Classic Edition - Definitive Guide
You can spend money on items such as weapons (then paint jobs and attachments), maps, etc. Items can be purchased at shops (of which there is one in the first village) and self-serve kiosks in liberated villages. Simply spend a total of $5k and the achievement will unlock. I spent most of my money at self-serve kiosks and it took me a couple hours.
This should come naturally as you play through the game. Even if the guns become free due to you taking over Outposts, each one will have something you can buy to customise it. This is accumulative, so you not have to spend $5000 all in one go.