The last shop was narrow and shabby. Peeling gold letters over the door read Ollivanders: Makers of Fine Wands since 382 B.C. A single wand lay on a faded purple cushion in the dusty window. (The Sorcerer's Stone, 82)I was in third grade the first time I encountered the Harry Potter series. I remember thinking even then that it was surprising there was only one place you could buy a wand, a crucial magical item for every witch and wizard!
Of course, we later learn there are other wand makers as well, such as when Victor Krum brags about his wand: "I vos one of the last to purchase a Gregorovich vand. They are the best - although I know, of course, that you Britons set much store by Ollivander" (The Deathly Hallows, 150).

What a monopoly!
Considering the fact that presumably each young witch or wizard only buys one wand in their lifetime though, Hank Green brings up another great point about the pricing of wands:
Well you don't seem to have much industry
[...]
I don't understand how any business gets done
when a wand only costs seven galleons.
That doesn't seem like much to me.
Mr. Ollivander not only makes and sells wands, but he also has a keen memory of them, as he tells Harry, "I remember every wand I've ever sold, Mr. Potter. Every single wand" (The Sorcerer's Stone, 85).
Making a wand is an awful lot of work, including dangerous foraging for magical cores for the wands:
"Ah, now, this is one of mine, isn't it?" said Mr. Ollivander, with much more enthusiasm, as Cedric handed over his wand. "Yes, I remember it well. Containing a single hair from the tail of a particularly fine male unicorn...must have been seventeen hands; nearly gored me with his horn after I plucked his tail." (The Goblet of Fire, 309)
Tomorrow, a mysterious magical item will be featured on the blog: P is for Pensieve.