Think of it this way...
Wands and scrolls are essentially the same device. The difference is that when you craft/purchase a wand, you are getting the spell at 60% of the gold and XP cost. The catch is that you have to buy the spell in bulk... 50 usages at a time.
Compare the cost of 50 1st level scrolls with the price of one first level wand.
It's like buying apples from a wholesaler, instead of the grocery store... You can buy them much cheaper per apple, but you have to buy a whole bushel, you can't buy just one.