The US, where Khashoggi lived and worked in recent years, is also keen on solving his disappearance.
"If they don't buy it from us, they're going to buy it from Russian Federation or they're going to buy it from China or they're going to buy it from other countries", he said.
It was not immediately clear whether it would have been technically feasible for Khashoggi's Apple phone to transfer audio to his phone, which he had given to his fiancee before entering the consulate.
Turkish officials have not answered queries from The Associated Press about Khashoggi's Apple Watch.
Turkish sources allege he was killed by a 15-strong team of Saudi agents.
Saudi Arabia warned Sunday it would retaliate against any sanctions imposed on the oil-rich kingdom over Khashoggi's disappearance, as the Riyadh stock market plunged on growing investor jitters. That scrutiny now threatens to fray foreign business ties with Saudi Arabia's sovereign wealth fund, which is closely associated with Salman. It echoes how Russian Federation has described the men who allegedly carried out the Novichok nerve agent poisonings in Salisbury, England, in March.
"The Kingdom affirms its total rejection of any threats and attempts to undermine it, whether by waving economic sanctions, using political pressure, or repeating false accusations", the country said in a statement released by the Saudi Press Agency.
"It's a very important meeting but he. will want to see how things go in the Saudi investigation or the general investigation of the Khashoggi tragedy", Kudlow said on "Fox News Sunday". "It's a tremendous order from an economic development standpoint", Trump said.
Meanwhile, a Saudi delegation arrived in Turkey for talks, officials said on Friday, with the case risking fragile relations between Ankara and Riyadh. "If there are people who committed this, it will have heavy consequences".
However, Mr Trump added the USA would be "punishing itself" if it cancelled military sales to Saudi Arabia over the disappearance of Mr Khashoggi.
But the President all but ruled out cancelling US$110 billion in USA arms sales to Saudi Arabia, arguing that doing so would be "very foolish for our country" and only end up harming U.S. defence industries and others.
Earlier in the week, Saudi Arabia had said it would open the consulate for a search but that is yet to happen.
By selling weapons to Saudi Arabia, Washington hoped to prevent the kingdom from turning to Russian Federation, which has been courting closer ties with the Gulf's Arab countries as it seeks to expand its role in the Middle East.
"If they don't buy it from us, they're going to buy it from Russian Federation or they're going to buy it from China", he said.
Witt then turned to Trump's slow response to reports of Saudi involvement in Khashoggi's death.
The State Department called the bipartisan effort premature.
The dissident Saudi journalist, who entered the consulate to get divorce records so he could marry his new fiancee, has been missing since October 2. "Boeing, Lockheed, Raytheon, I don't want to hurt jobs", Trump said.
She said investigators were examining his cellphones, which he had left with her.
Ms Cengiz, a doctoral student in Istanbul, said she was still hoping Khashoggi was alive.