How much would it cost for a head forehead reduction?

In general a forehead reduction surgery costs in the $10,000 range.  Maybe higher.  Maybe lower.  It all depends on your examination and what each doctors charge for the surgery.

Forehead reduction surgery comes in two types, the first is a surgical procedure that gives you same day results, the second is a hair transplant that takes 6-7 months to see. For men, my main concern for men who have a hairline advancement surgical procedure is in the potential balding that may occur as most balding can start at any age and advance until the mid-fifties. If that happened to you (your risk regardless of your sex) then you will have to get a hair transplant to cover it as a scar from a hairline lowering surgery will show with a receding hairline as the frontal area is the place that genetic balding starts in most men.
For young men, this chance of this happening is fully 99% over time so a surgical hairline lowering is not the procedure of choice in men for a receded hairline and many times, unless you are over 40, you will not really know. The scars that appear, are permanent and you need a hair transplant to cover it, burying it in the new hair placed by the hair transplant. With regard to hair loss following such surgeries, in women it is not common, but it does happen, in young men under 35, it is very common.