Kawoh,

The taxis are safe, just that they're not legally allowed to pick up passengers at KLIA. Fares are of course negotiable. They'll start pretty high, but you can knock off quite a bit. There'll be an announcement made by the airport authorities advising you NOT to use them, but if I read your post correctly, you want the cheapest way to get to Seremban right? I don't think they come cheaper than that.