Leak of Power steering fluid; tube replacement suggested by Dealer's repair shop. on 1998 Toyota Avalon

What is a fair charge for this? If there's a leak, can't the area where it leaks, be sealed? Is it necessary to replace the entire "tube section" for a total charge of over $500? THis is the first time ever for this problem.
Please advise. [The car has always done very well, with its check -ups before.]

Asked by for the 1998 Toyota Avalon
Can you be more specific for what "tubes" are being suggested?
1 more answer
You may need to replace rack and pinion which failed on my Avalon after 8 years. Common symptom is loss of power steering fluid. Cost was about $750.