theory11 — Magic Tricks & the World's Finest Playing Cards

What would you recommend a magician to buy?

it depends on what the magicians style is, and what he likes.

I would have to go with Stigmata and fraud

two really great tricks that I think almost anyone can use.

very easy to do too
 
My vote would go to the Mark Wilson complete course in magic or the Tarbell course in magic. Both have more magic than one person can handle.
 
Paul Harris' Art of Astonishment. There is so much creative thinking involved with everything he packed in there. It provides a great foundation for any magician to build on.

Peace
:)
 
Perhaps a deck of cards would be useful to have as a magician...

But in all seriousness, I would highly recommend the Classic Magic of Larry Jennings. Yes, it's "old school," but there are ideas in there that have enhanced my magic beyond anything I would have expected.
 
One thing a magician needs to buy? A deck of cards! I'll assume though, that he/she already has one.

Royal Road to Card Magic....or Card College...depending on finances