Access Everyone’s Budget
Unless you and your roommates are all working at the same place, with the same position, and have the same family background, there is going to be a difference in everyone’s budget. Although it might a little awkward, you should all be frank about how much each of you can afford to spend on decorating. The group should either spend an equal amount for communal spaces, or if someone can afford it and wants to purchase more items, work out an agreement amongst everyone about what items each roommate can take if they move.