I'm not really sure how to write a guide for this because it's pretty straight forward. I suppose that it will be similiar to the guide that I wrote for 'Purchase 50 female outfits'.
I will say this, though: If you can find a street challenge that is very quick and easy to do, you can make enough money to get this pretty quickly. I use Cepheus St. 1 for this. It will only net you 1200 per run, but it takes about 90 seconds to get though it, including front and back load times. Given the varied cost of the outfits, it's about 120 times if you don't spend the money on club challenges. If you are really looking for this achievement, that's not much at all. Plus, you're halfway to the 'Purchase 200 female outfits' achievement.