Where exactly do fantasy wizards get their magical supplies? It’s a question that has interested me for a while, and one that can have some fun repercussions if you answer it in your own fantasy. After all, what self respecting wizard spends all his time wandering around poking newts’ eyes out when he could be back in the tower chanting something incomprehensible in front of an open brazier?
Apprentices are one answer to this issue. Just send the poor lad or lass out to collect Instant Death Weed by moonlight, the way you had to as a boy. It certainly allows for some fun stories with slightly put upon protagonists.
Another option is the specialist magic shop, full of handy stuff and with an uncanny similarity to whatever real world shop you want (one of Pratchett’s wandering shops reminds me faintly of Aunty Wainwright’s place out of Last of the Summer Wine). I must admit to really loving these places.
Finally, your wizard could just get it all out of a catalogue. It probably explains what all those big, thick books are, come to think of it.