It’s not too hard to find what you need inside Powell’s City of Books in downtown Portland, Ore. That’s saying something, since it’s home to approximately one million titles, divided into 3,500 sections and engulfs a city block.

When you want to find something you learn to rely on the staff. But when I asked three different employees for the location of the store’s most expensive book — I got three different answers.

“We’re not just going to draw you a map and say to somebody ‘if you want it come and get it,’” said Michael Powell, the former president of the family-owned store.

Michael Powell keeps the Lewis and Clark journal in a secret room.

Inside a room unknown to staff and customers, Powell pulls the book, or more specifically a two-volume set of the 1814 Lewis and Clark Journals, from bubble wrap. The books were published eight years after the explorers’ returned. Only about 1,500 copies of this edition were sold.

“This version is extremely rare. We think it might be the only one left in private hands,” said Powell. “This edition has the map, which I will not unfold.”

He said one tear in the map could potentially cut the price of the set in half. It’s not a risk he’s willing to take on a journalist. He’s asking $350,000 for the set. That means hardly any customers or employees will ever see it. But its presence is still significant to the store.

“People are always asking us what’s our rarest book? And so, it’s fun to say it’s an edition of the Lewis and Clark journals as opposed to say a 14th century, 15th century German religious tract or something,” he said.

There are two big factors contributing to the steep price tag. The first is that map Powell mentioned. The printed map was drawn during the journey by Captain Clark. At the time, this was the most accurate snapshot of the Western interior in the United States.

What makes the Powell’s copy so expensive is not only that it includes this map — and the original covering — but that it’s in terrific condition.

“The journals themselves with the map is just a very rare historical document,” said John Logan Allen, a Lewis and Clark scholar and author based in Wyoming. “[Most] of them were probably destroyed. So there simply aren’t many existing copies.”

But is it $350,000 rare?

“I’m frankly surprised that Powell’s put this price tag on it,” Allen said. “I’m just not certain it’s worth the money.”

But you never know what it might be worth to a devoted Lewis and Clark collector. And they’re out there — people like Roger Wendlick, who once spent years seeking Lewis and Clark printed materials.

For a blue-collar construction worker from Portland it turned into a big problem.

Roger Wendlick, who collected Lewis and Clark printed materials, outside Lewis and Clark College in Portland.

“I was insane. I was addicted. It was a passion beyond control,” remembered Wendlick. “I had 11 credit cards … They were all maxed. I had refinanced my house — twice — getting ready for the third time so I could have more money to buy books.”

Wendlick bought a copy of the 1814 journal, like the one at Powell’s, on a handshake. He paid for it in monthly installments. Eventually, Wendlick parted with it — and the rest of his collection—in a deal with Lewis and Clark College, as part of a half sale, half donation. He estimates that book is now worth around $200,000.

Michael Powell may have set a high price for his volumes because he isn’t really angling to sell. After all, they’re a part of Oregon history. But business is business and Powell said the set is very much for sale.

“Somebody said ‘Wouldn’t you feel bad?’ Well, that price would heal a lot of wounds,” said Powell.

He wraps up the journal and locks it back in the safe where it will sit until a buyer comes to the secret room. If that buyer is serious enough, he might even unfold the map.