The phrase "ever more expensive" is correct and can be used in written English.
It is often used to describe something that is getting progressively more costly over time. Example: "As technology advances, smartphones are becoming ever more expensive, making it difficult for some people to afford the latest models."
Worse, new kit is becoming ever more expensive.
Air travel remains a necessity, even as it gets ever more expensive.
For most Russians, whose salaries are denominated in roubles, imports are becoming ever more expensive.
Education, housing, and health care – essential ingredients for individual success – are growing ever more expensive.
As long as lawmakers do nothing, the state's problems will become ever more expensive and ever harder to solve.
Inheritance-tax laws were tightened in 1998, and tougher regulations make maintaining old houses ever more expensive.
This budget is an attempt to return us to the failed policies of the past – unsustainable growth based on dwindling and ever-more expensive resources.
But what worries Ms. Friedman — whose critically acclaimed transfers from London have included the Tony Award-winning Cagee aux Folles," "The Norman Conquests," and "Boeing-Boeing" — is that Broadway is ever-more expensive for producing than London.
But instead of catching up to terrorists with ever-more expensive gadgets and ever-most annoying restrictions, the agency could try imitating the Israelis, who focus on intelligence-gathering rather than shampoo confiscation.
Ultimately, the mass militaries of the modern era, augmented by ever-more expensive weapons systems, place an unacceptable economic burden on the nation-states that support them – a burden that eventually may undermine the militaries themselves.
The industry is moving toward ever-more expensive manufacturing technologies.
