The sentence "is highly expensive" is correct and usable in written English.
You can use it to describe something that costs a lot of money. For example, "This restaurant is highly expensive; dinner for two can cost over $100."
The operation is highly expensive, but Mr Steptoe believes several thousand women a year could soon be benefiting from it.
The cannabis-based drug Sativex, which can be used to help relieve the symptoms of multiple sclerosis, can be prescribed by GPs, though it is highly expensive.
The idea of making the payroll tax deductible has been considered, but discarded, in Congress, both because it is highly expensive and because deductions favor taxpayers in upper brackets.
This is highly expensive compared with the cost of providing necessary benefits and support to help someone to continue to live with self-respect, as a contributing member of the community.
Providing these requirements is highly expensive.
The price of the embassy method is highly expensive and very discouraging for the poorest illegal migration candidates.
They will be highly expensive, and unlucky health breaks will be all the more tragic because not everyone will be able to afford the best treatments.
But such a deal would have been highly expensive, and Schneider quickly abandoned the effort after reports of the discussions surfaced.
"It's no surprise the government is saying that programs that are highly expensive and give a Rolls-Royce treatment to citizens have to be trimmed," said Iain Begg, a professor at the London School of Economics.
"Luxury products are highly expensive and civil servants, whose salaries are about 5,000 yuan (or $793) a month, cannot afford them," the China Daily newspaper reported Friday, using another term for the renminbi.
The beverage, produced in the Scandinavian countries, derives its name from aqua vitae (Latin: "water of life"), applied originally to liquor distilled from wine, and was made from imported wine; the product therefore was highly expensive until Swedish soldiers learned to make aquavit from grain.
