[Oh, you're enthusiastic. He almost smiles a little, clearly amused]
Don't worry about it, kid. [He's just lingering around because despite coming from a world without magic, he likes learning about it. So this kind of thing is interesting to him, the rambling of ingredients aside]
You can also just ask Merlin if you're looking for other stuff. He might know. [Even though he only got this shop like an hour ago, but hey.]