That's for a liter of gaseous deuterium. According to the note in the last column, "Also sold by same supplier in the form of heavy water at price of 3940 USD per kg deuterium." Since a kilogram of heavy water is ~20% deuterium by mass, that means $788 per kilogram of heavy water. That would only come to $394 million for 500 metric tons of heavy water, significantly lower than the $1.5 billion found by kennend3.
The higher price kennend3 found could reflect the fact that Canada manufactured its own heavy water for building CANDU reactors in the 20th century whereas today there is more heavy water manufacturing capacity, including a large and relatively new plant in India: https://www.hwb.gov.in/heavy-water-plant-manuguru
Oh they have tried. Collecting various forms of hydrogen by separating heavy water has had government/military funding for decades. The basic physics has been worked out. There is no low-energy option anymore than there is a low-energy way to separate uranium isotopes.
The original heavy water plant in Vemork, Norway recovered it as a byproduct of producing hydrogen from water by electrolysis [1] for the manufacture of fertilizer. Ordinary "light" hydrogen is preferentially evolved from water when it's split by electrolysis, with deuterium accumulating in the liquid left in the cell. If the plant operator periodically extracts the residual water from a cell and uses it as input to another cell in a cascade arrangement, as done at Vemork, then high-purity heavy water can be generated as a byproduct of electrolysis with little additional cost. The Vemork plant had 108 megawatts of capacity and could produce 12 tons of heavy water per year ([1], [2]).
I expect several gigawatts of electrolytic hydrogen capacity to be built this decade for supporting "green" production of steel and ammonia with renewable electricity. Plant operators could also invest a modest effort to extract and concentrate older electrolyte batches, providing a new low cost source of heavy water. Note that this is a very energy intensive way to get deuterium, but it could be low cost because the capital and operating expenses are mostly accounted for by the plant's primary purpose (hydrogen production). The marginal cost to add a side business of heavy water recovery would be much smaller.
The book The Winter Fortress about the sabotage of the plant by Norwegian commandos makes my personal list of greatest stories ever told. It also makes me want to learn to cross country ski.
Like, nine guys went in and blew up the plant, and then skied across the trackless wilderness to neutral Sweden. All the while working under conditions that might be charitably described as austere.
I reread it every couple of years and cannot recommend it highly enough.
The higher price kennend3 found could reflect the fact that Canada manufactured its own heavy water for building CANDU reactors in the 20th century whereas today there is more heavy water manufacturing capacity, including a large and relatively new plant in India: https://www.hwb.gov.in/heavy-water-plant-manuguru