This description is a little vague and may cause some confusion. You are required to at least 1 house with each star rating. The houses in the game are given upto a 5-star rating and you'll be required to purchase a house with a 0, 1, 2, 3, 4 and a 5-star rating.
As you will have the Caravan from the start of the game, you have 1 0-star rated house.
To buy a house, you can either find it in free-roam or visit your local Estate Agency in the "Spots for Avatar" tab in your Map ().
Here is a list of the cheapest available houses in each star rating;
0-Star: Caravan (Should have this house from the start of the game)
1-Star: Fontanelles house - $95,000 - Ibiza Area 1
2-Star: Refuge house - $198,000 - Ibiza Area 2
3-Star: Tropical House - $311,000 - Hawaii Area 3
4-Star: Kahuku Point Paradise - $1,110,000 - Hawaii Area 2
5-Star: Yacht - $5,000,000 - Ibiza Area 1 **
** There is a way to save money if you want to keep your cash from buying the Yacht.
Make a copy of your save game BEFORE you buy the houses onto another Storage Device. Then load up your game on your COPY device, buy all of the above houses for the achievement, then refer to your MAIN save, to have the money from before.