These 2 magnificent seven AI stocks might be offering investors a once-in-a-decade buying opportunity before the New Year.

This article was originally published on Fool.com. All figures quoted in US dollars unless otherwise stated.

The Magnificent Seven technology stocks have powered the S&P 500 through this bull market so far -- that's because investors like their solid, well-established businesses and their promise in the high-potential artificial intelligence (AI) market. Some are bigger AI players than others, but they all are participating to some degree in this technology. Investors are enthusiastic about AI because it may supercharge earnings and stock performance over time.

And, as mentioned, the stock performance already has started, with the Magnificent Seven stocks each advancing in the double- or triple-digits over the past three years. This is great, but it's resulted in one thing that may be holding investors back from buying at least certain players right now: Stocks have become more expensive.

In fact, some analysts and investors have even worried about an AI bubble. Those concerns weighed on the S&P 500 in the early weeks of November, though tech companies' earnings reports and comments on demand haven't supported the idea of a bubble taking shape. Earnings have climbed, and companies have spoken of high demand for AI products and services.

Still, it's clear many AI stocks are expensive these days. But the good news is bargains also exist -- even among Magnificent Seven AI stocks. And two in particular may be offering investors a once-in-a-decade buying opportunity before the new year: They are the cheapest of the Magnificent Seven, but due to their potential in AI, this may not last for long. Let's check out these stocks to buy now. 

1. Meta Platforms

Meta Platforms (NASDAQ: META), trading for 26x forward earnings estimates, is the cheapest Magnificent Seven stock today. This is a fantastic deal considering the company's long history of earnings growth, which offers it the ability to invest in AI and reward shareholders with dividends.

You may know Meta mainly for its social media leadership -- the company owns a number of apps, including Facebook and Instagram -- and this platform has been its ticket to revenue growth. Advertisers come to Meta to reach us, and this has resulted in billion-dollar revenue and profit for the company.

Meta now aims to use AI to revolutionize advertising, automating ads across its platform and making them more successful. Meanwhile, the presence of AI on its apps may keep us on them longer. All of this may result in advertisers increasing their spending on ads here. And Meta's investments in AI also could lead to the development of new products and services that may drive revenue down the road.

All of this makes Meta look like a steal at today's valuation.

2. Alphabet

Alphabet (NASDAQ: GOOG) (NASDAQ: GOOGL) is the second-cheapest of these seven tech titans, as it trades for 29x forward earnings estimates. Like Meta, Alphabet may not remain at this level for long as its AI investment powers revenue higher.

Alphabet uses AI across its Google Search business, and that should boost advertising revenue as it takes a route similar to Meta's -- improving the overall advertising experience and ad results. And Alphabet also is benefiting from AI through its Google Cloud business -- here, it offers a wide range of AI products and services to customers, and these have been fueling revenue growth.

In the latest quarter, for example, Google Cloud revenue climbed 34% to more than $15 billion, and for the first time ever, Alphabet reached total quarterly revenue of more than $100 billion. As a leading cloud player, Google Cloud should be well-positioned to attract AI customers looking for capacity -- demand already has been surging and hasn't shown signs of letting up. In the quarter, Alphabet said demand for AI infrastructure and generative AI systems drove cloud revenue.

So, Alphabet, like Meta, is on track for more growth as this AI boom marches on -- and that means getting in on these stocks at today's levels may be a once-in-a-decade opportunity.

This article was originally published on Fool.com. All figures quoted in US dollars unless otherwise stated.