Warren Buffett once joked that Charlie Munger's 'idea of traveling in style' was an air-conditioned bus

• Charlie Munger, Warren Buffet's long-time business partner, died at 99 on Tuesday.
• Munger was known for being relatively frugal despite his wealth.
• In 1989, Buffett quipped that Munger saw air-conditioned buses as luxury travel.

Charlie Munger, the vice chairman of Berkshire Hathaway and Warren Buffett's decades-long business partner, died on Tuesday in California. He was 99 years old.

Munger and Buffett had been friends for over 60 years, first meeting in 1959 at a dinner party. Munger joined Buffett at Berkshire Hathaway in 1978, where he served as Buffett's second-in-command for decades.

And like Buffett, who is famously frugal, Munger was known for his relatively conservative spending habits despite his wealth. Munger's net worth at the time of his death was an estimated $2.2 billion, as Forbes reported. The outlet also notes that Munger's fortune decreased over the years as the billionaire donated much of his money to universities.

Munger's cautious approach to money cropped up in his work at Berkshire Hathaway, as evidenced by his and Buffett's dueling opinions on the company's acquisition of a corporate jet in the '80s.

In a 1989 letter to Berkshire Hathaway's shareholders, Buffett reviewed the company's decision to sell a jet it had purchased three years earlier for $850,000 and replace it with a different, used jet that cost $6.7 million. Buffett said Munger found the purchase extravagant, pointing to his business partner's travel habits.

"His idea of traveling in style is an air-conditioned bus, a luxury he steps up to only when bargain fares are in effect," Buffett wrote of Munger.

The Berkshire Hathaway chairman and CEO poked fun at Munger later in the letter as well.

"Naming the plane has not been easy," Buffett wrote. "I initially suggested 'The Charles T. Munger,'" he added, referencing Munger's middle name, Thomas.

He continued: "Charlie countered with 'The Aberration.' We finally settled on 'The Indefensible.'"

Despite his apparent love of budget buses, Munger traveled on planes throughout his life and was involved in the aviation industry, as Berkshire Hathaway's portfolio includes the private-jet company NetJets and other plane-related businesses.

And later on, in the same 1989 letter to the company's shareholders, Buffett wrote about a valuable piece of investment advice Munger shared with him.

"It's far better to buy a wonderful company at a fair price than a fair company at a wonderful price," he wrote. "Charlie understood this early; I was a slow learner."