Nothing too difficult, just have to make sure you’re grinding out challenges in order to make the most money.
Majority of the items in the store costs $100 each so you’ll be looking at having to purchase 100 different items in order to get this achievement.
If you’re buying socks, which are $50 each, try to buy 2 at a time so you can keep your total at $100 increments so it’ll be easier to keep track of how much you spend. You can also look at the percentage completed and calculate your total spent based on 1 percent being equivalent to $100 spent.