Cost is a parameter subject to engineering tradeoffs, just like performance, feature sets, and implementation time.

Security and reliability are also parameters that exist on a sliding scale, the industry has simply chosen to slide the "cost" parameter all the way to one end of the spectrum. As a result, the number of bugs and hacks observed are far enough from the desired value of zero that it's clear the true requirements for those parameters cannot be honestly said to be zero.

The question was not if it was possible within price boundary X, but if it was possible at all. There is a difference, please don't confound possibility with feasibility.

Also people keep insisting on using unsafe languages like C.

It depends on exactly what you are doing but there are many languages which are efficient to develop in if less efficient to execute like Java and Javascript and Python which are better in many respects and other languages which are less efficient to develop in but more efficient to run like Rust. So at the very least it is a trilemma and not a dilemma.