Earlier this week the real estate website Movoto.com had some fun trying to set a smart listing price for the White House. To do so it recruited a luxury homes expert who proposed $110 million, and then said he'd expect a sale price somewhere between $75 million and $80 million.

The thing is, that's ridiculously low. Earlier this year a Russian billionaire dropped more on a penthouse apartment in Manhattan. Granted, real estate prices are higher in New York than Washington, D.C.—but c'mon!

There's a key lesson here for entrepreneurs. Figuring out valuation is tough. We ask ourselves over and over: "What are our products and services worth to customers?" And maybe someday, if we do well, "What is my business worth to a prospective buyer?"

I've been working on a writing project with Ken Marlin, managing partner of Marlin & Associates, a boutique financial and strategic advisory firm. With this White House story in mind, I asked him to talk about how to put a smart price tag on just about anything—especially when there is no active market shaking things out for you.

Here's the five-point, back-of-the-envelope plan he came up with.

1. Understand precisely what's special about the asset.

Movoto's expert estimated the listing price based on the White House's size and location, but of course that has almost nothing to do with why someone might theoretically want to buy it. They'd do so for the history and the symbolism. (Wouldn't you love to be a fly on the wall as a listing real estate agent walked through the White House, suggesting that it be staged a bit differently, or that that facade would be more striking if it were painted a nice robin's egg blue.)

"You've got to know what's really cool about the property, or about the business," Marlin said. "And, that's what you have to make sure you highlight and communicate to potential buyers."

2. Understand the range of potential buyers.

The flipside of this is that you have to figure out how the asset—whether it's real estate or a business—would fit into a potential buyer's portfolio.

If you're selling a business, for example, you might find that potential buyers might want to acquire you for purely financial reasons. Others might want to acquire you strategically as part of a plan to continue building their businesses.

As for the White House, Marlin said, think about who might line up to bid on it.

"You'd have hugely wealthy Russian oligarchs. Donald Trump would want it as condos with a golf course on the South Lawn," he said.

3. Create a market of those potential buyers.

Valuations are always tough when there is no functioning market, and thus no comparable sales to point to. So a smart entrepreneur, whether he's trying to sell a company or a piece of iconic real estate, tries to create one.

Often, that means staging an auction. You don't need hundreds of potential buyers: just two, although having more is better.

"When we advise sellers, we tell them you want an auction. When we advise buyers, we say you want to avoid an auction," Marlin said.

4. Be trustworthy, and create bidding comfort for buyers.

Whoever buys the asset—whether it's the White House, a product you're selling, or your business—wants to pay as little as possible, of course. But there's a second factor that a potential buyer considers in coming up with a bid: He or she doesn't ever want to look like an idiot.

So your job as a seller is to give them a good-faith basis for your asking price or listing strategy. And, you need to negotiate in such a way that the potential buyer understands you could legitimately walk away.

"Nobody wants to look stupid," Marlin said. "So, if you're asking them to pay twice as much as the guy down the street, you need to give them a reasonable basis for that."

5. Remember: You're trying to sell the future.

Here's where the strategy diverges a bit between selling something like the White House and selling a business. With the White House, a buyer would mostly be buying the past.

But while business buyers need to understand your asset's history, they're only interested because they need to understand the future.

"That's what they're buying—the future. And a buyer always has a fear that you know something they don't–that you're selling at the top of the market," Marlin said. "They don't care about the past. From a business perspective, from a corporate perspective, you have to help a prospective buyer see the future the way you see it."

The bottom line, Marlin told me, is that putting a price tag on just about any asset is, well, about much more than just the bottom line. So you'll do yourself a service by thinking long and hard about the people involved in the transaction.

"Valuation and negotiation are as much about the human element as they are about math," Marlin said. "Probably more about the human dimensions. You can't just apply the math and say, 'My competitor sold for 12 times EBITDA, so multiply my EBITDA by 12.' It just doesn't work that way."