かかる (Time/Price)Costs (money), Takes (time)

かかる is a verb that has many different uses. One common use is to say that something takes time or money. The core meaning of かかる is 'to hang', or 'to rest (weigh) upon'. When applied to time or money, the idea is that something weighs upon the subject, acting as a burden or requirement for completion.

As かかる is an intransitive verb, a general noun representing time/money/value will be marked by the subject-marking particle が.

Specific amounts of time/money expressed with counter words can also be used. However, when used with counter words, が is normally dropped entirely (a common pattern for counters in general). It may help to think of the counter as being used adverbially here, describing the verb/action itself and not acting as a noun.