Just to be honest with you, I've NEVER seen a turbo setup for an SC400 go for less than $1000. A complete set has always been much more than that to my knowledge. If you want a good setup it may run you a little higher. This is the cheapest one I've seen around, it's used on the club lexus forums. Hope it helps.
http://www.clublexus.com/forums/showthread.php?t=284863