Half Price Day
On the third day of every month for one day only, every store in Neopia (or at least, all of the stores restocked automatically) cuts its prices in half. This is a great chance to make a major profit off of some of the very expensive rare items that can be sold in your shop for many more Neopoints than you spent on them.
The Hidden Tower and Smuggler's Cove are the only two "shops" that don't cut their prices in half.