Let's first assume that a Spirit Stone is worth ten thousand in the Embracing the Void realm, an amount a well-off family could earn after several months of hard work, and it's possible to buy one without being too unaffordable.
In the Tianyuan realm, one Good Deed equals one hundred Credit Points, which makes living comfortably for a day a bit difficult, but at least there's no worry about food and clothing.
An Jing was just making deductions, he had no references and could only rely on the memories of his previous life to crudely estimate the prices, which were certainly very inaccurate.
He roughly estimated, "And in the Tianyuan realm, one liang of Airy Stone is valued at one thousand five hundred Good Deeds… if one Good Deed is considered equal to one hundred yuan, the Airy Stone is worth one hundred and fifty thousand. And that's just the empty ones, it wouldn't be strange for a complete Spirit Stone to double in value."