Stocks can make fools of even the smartest people. Many have been calling the current market a bubble for years. The price-to-sales (P/S) ratio of the Nasdaq Composite reached 2.6 in 2007 before crashing. It surpassed that by the end of 2015, leading many to point to another imminent collapse. Since then, the Nasdaq Composite is up 190%. That P/S ratio is now double what it was in 2007. There is a reason timing the market is considered nearly impossible. 

It's why Warren Buffett has said it's better to buy a great company at a fair price than a fair company at a great price. Over time, the advantages of those great companies will keep compounding. As another great investor puts it, "winners keep on winning." That's why now might be a good time to add two great Nasdaq stocks -- Amazon.com (NASDAQ:AMZN) and Inari Medical (NASDAQ:NARI) -- to your portfolio despite the sky-high valuations of the overall index.

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1. Amazon

Amazon needs no introduction. It virtually defined online commerce and cloud computing over the past two decades. Despite already being such a window into the American economy, it has become even more important during the pandemic. That's evident by the ridiculous numbers the nearly $2 trillion company has been putting up. Revenue in 2020 was up 38% year-over-year. The momentum carried over into the first quarter, when the company posted 44% sales growth. 

Amazon's trailing-12-month revenue is $419 billion. After it reports earnings this week, that number should jump to at least $446 billion. It's almost double what it was in 2018. At the current stock price, that would give the company a P/S ratio of 4.0. That's inline with its average of the past three years.

AMZN PS Ratio Chart

AMZN PS Ratio data by YCharts

Long-term outperformance is about buying great companies at a reasonable price. Everyone would love to have another chance to add shares at the pandemic lows, but it could be years before investors get another opportunity like that. Even then, the share price could be much higher than it is now. That's why it's time to take advantage while the shares are reasonably priced. Once Amazon reports earnings Thursday, its stock may once again command a premium.

2. Inari Medical

Inari's $4 billion market cap is tiny compared to Amazon. Unlike the everything store, it has helped clinicians achieve one primary goal: remove large clots from veins without using dangerous blood-thinning drugs.

Its two disposable systems -- ClotTreiver and FlowTreiver -- have led to sales growing twentyfold from 2018 to 2020. Revenue grew 113% year-over-year in the most recent quarter. Despite the torrid growth, the stock has been struggling recently. It's down about 9% since it reported those first quarter earnings in May compared to a 9% gain for the Nasdaq overall.

Thanks to the combination of huge revenue growth and the drop in the stock price, the PS ratio is at 22. That's the lowest level investors have been able to buy shares since the company went public in May 2020. When Inari delivers its second quarter report, that ratio should drop to at least 20.

NARI PS Ratio Chart

NARI PS Ratio data by YCharts

It is still an elevated ratio for a company that isn't selling software, but its 90% gross margins and greater than 100% sales growth make it an unusual bargain relative to its 14 months as a public company.

For investors scanning the horizon for relative value in an expensive market, Inari Medical offers hypergrowth and profitability at a relative discount. The stock is already my second largest holding. But for those who don't yet have a position, now could be the perfect time to add one of the best buys in the Nasdaq.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.