Since you didnt provide the info, Im gonna guess he wants 36 subs, and he want's 18's. 36 subs at $150 each is a pretty big budget. That's enough to just buy a JackHammer, that's what id do if I was your friend. 2 cubes would be on the small side for 36 18's anyway.Need sub suggestions for a friend.
He'll be running around 1000-1500 watts. They will be in a smaller enclosure, and sealed... probably 2 cubes total.
Price range is... No more than 150 per.