The most common and most likely answer to this crossword clue is the 8 letter word SKY-HIGH
I've seen this crossword clue in The Times
S
K
Y
-
H
I
G
H
Buddy explains!
The straight part
We know that "such costs are very steep" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case such costs are very steep = sky-high.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does SKY-HIGH mean?
SKY-HIGH adjective- Extremely tall
- Excessive, exorbitant