Rack and pinion problems

My '94 (334,000 miles) has worn out yet another passenger side tie rod. Up to now, when I have had to repair a rack and pinion, I have replaced the entire thing, to and include the linkage to the base of the steering wheel. This is a pain, hense this question. Do you guys replace the entire rack and pinion or do you just replace the tie rod? And if you just replace the tie rod, do you buy these new or from the junk yard?