One breast is saggy and the other is perky. What do I need done and how much would it cost?

Hi. Thank you for your question. It is very hard to give any recommendations without pictures. Usually a breast lift is needed to correct saggy breasts. I would recommend you to consult with a board certified plastic and reconstructive surgeon. All the best
Dr Marco Carmona MD 

Without the opportunity of at least seeing photographs of your breasts from the front and side, and better yet a personal examination, it's impossible to answer your questions with any reasonable accuracy.
Asymmetry of the breast can be treated in a number of ways according to the individual problem(s). You may need implants with a unilateral mastopexy. You may need implants with bilateral mastopexies, raising one more than the other. You may just need asymmetrical mastopexies with no implants. Or maybe you need fat grafts to make you more symmetrical. 
Possibly you need a reduction on one side. As you can see, the procedure is available are numerous and must be individualized.
I suggest you see a plastic surgeon certified by the American Board of Plastic Surgery and preferably a member of the American Society of Aesthetic Plastic Surgery for a consultation.
Thank you, and best of luck to you.

Hello and thank you for your question.  The
best advice you can receive is from an in-person consultation.  The solution for this will depend on your goals for the size of your breasts.  In patients with asymmetric breasts, sometimes a breast lift and/or implants can be beneficial.  Adding pictures would help in giving you more accurate advice.   This decision should
be based on a detailed discussion with equal input from both you
and your surgeon.  Cost varies based on geographic region and surgeon expertise.   Make sure you specifically look
at before and after pictures of real patients who have had this surgery
performed by your surgeon and evaluate their results.   The most
important aspect is to find a surgeon you are comfortable with. I recommend
that you seek consultation with a qualified board-certified plastic surgeon who
can evaluate you in person.
Best wishes and good luck.
Richard G. Reish, M.D.
Harvard-trained plastic surgeon