I haven't purchased a house yet even though I'm very advanced in the game and close to finishing it (the main quest and most of the bigger side quests at least)
Whenever I have excesses in my inventory I can just drop them in my Winterhold room or the other bigger room you get when you do that thing, so I never felt the necessity to buy another one (also, being a thief, I love to have lots of gold on me).
What good is it to buy a home?