I would recommend a few things; Many power steering pumps whine for years. Determine if this is a problem for your ears and whether there is any problem with how the car steers. As stated above, you might want to just wait, no need to spend money in advance of a failure when this kind of failure will be "progressive", not sudden. Meaning, if it is failing, it will get worse and worse, but give you plenty of warning by affecting your steering mildly or getting much louder before it stops working, not suddenly.
If deciding about fixing it; (A) Find the price of a replacement pump that satisfies your needs whether it is a rebuilt unit, or a used unit from a junkyard with a guarantee.
(B) If thinking about doing it yourself, Find out where the pump is on your car visually. Follow the hoses from the resevoir to the pump and/or look at manuals at parts stores to determine where the pump is. Get a $15 book from a book or parts store on fixing your model car or get one off Ebay. I suggest you see the pump's location with you own eye's (I don't know for your model ) to help determine if you want to tackle the job.
(C) Don't be shy, go to your mechanic, or another, and say something like "that's an expensive repair, is that a rebuilt pump? warranty? (if the labor is most of the cost, ask ) where is the pump anyway?, can you show me? Is it a difficult job?"
Try this with more than one mechanic until you are satisfied that you feel you have enough information to decide what you want to do.
(D) Determine if special tools will be required. Is the resevoir separate from the pump because the pump is at the bottom of the engine, but easily accessed once you get under the car? or is it in the middle of the front of all the engine accessories and will require you to pull the radiator and most of the front engine accessories to get to it?
As Mike said above, good wrenches will usually be needed, probably metric sized "line wrenches" which you may not have in your toolbox.
RedCrow