Being a werewolf could be pretty inconvenient. Without proper care you wake up in the forest naked and covered in blood. Even if you bother to chain yourself up, half the time your chains break, and the other half of the time you still wake up naked and covered in blood, only its your own. And since you need a guard to take you down if you happen to escape, lycanthropy is pretty inconvenient for those around you, too.
Not to mention them possibly getting eaten.
"Cures" for lycanthropy also pretty much suck, too. There was the method of the wizarding world, Wolfsbane, which only protects the werewolf's human mind. It was rare, and expensive because it was rare. Oz did not just want another kind of chains for his werewolf side. He wanted it gone. And if not that, controlled.
Oz's method could possibly cure his lycanthropy. Until the last full moon he had not transformed since he was at Sunnydale, and that was ok. Not good enough, but a nice start. Of course, the cure was a bit more inconvenient than Wolfsbane. Oz chanted daily several times a day, relied heavily on his various beads to keep him focused, and his precious tea to keep him calm.
This tea was made from herbs, which were rather rare, and expensive because they were rare.
Oz was running out of money.
He was walking towards the Owlery to prepare his owl for its weekly retrieval of said money-suckers when he heard a scream. It was high-pitched, nerve-wracking, and way too human. And the fact it came from the same area where he had been smelling Fenrir Greyback really brought a whole new level of suck to the situation.
Oz clutched his little-used wand and dashed to a huge ramshackle barn off to the side. It appeared to be locked, so he pointed his wand to the door.
"Alohamora!"
There's a first time for everything.