You'd have to look at it first. If it's cracked, replace it. If it's just leaking at the head due to a stud or bad gasket, keep it. I put a header on my brothers 98 in a few hours. That doesn't mean that a shop will only charge you a few hours, but you could always do it. It really doesn't take any crazy tools, and you would gain a little experience. It's really not that hard.
Chad