When a wizard/witch's wand is broken, what stops him/her from simply buying a replacement?

When a wand is broken as a punishment (like in Hagrid's case), what prevents that witch or wizard from simply buying a new one? Even if there was a record telling Olivander not to sell them a replacement, they could go abroad instead. Or if they had the right knowledge/connections they could even make their own. Or a friend/relative could get a new wand, claiming that their original was broken in an accident, and give the replacement to the wandless wizard/witch (I know it wouldn't work as well, but it'd be better than no wand).