XL breast implants 800cc cost? (Photo)

Although the posted photograph is limited, it does appear that you have a moderate degree of bresat asymmetry; it is possible that breast lifting of the lower breast may be necessary to improve your breast symmetry.Generally speaking, every patient undergoing breast augmentation surgery should understand that their anatomic starting point will limit the outcome of breast augmentation surgery.    In other words, a patient's starting anatomy will limit how large of a breast implant can be utilized safely. The use of a larger breast implant (than what is safely "allowed" by the patient's anatomy) can be problematic;  potential problems include breast implant displacement/malpostion issues ( such as bottoming out, lateral displacement, symmastia...)  and/or significant breast implant rippling/palpability.
Generally, in my practice, I suggested patients aim for an outcome  only as large as "necessary" to make them happy;  pushing the envelope again can be problematic.  Sometimes, more than one operation is necessary to achieve the patient's desired "extra large" or "fake" look.Generally speaking, the best online advice I can give to ladies who are considering breast augmentation surgery ( regarding breast implant size/profile selection) is:
1. Concentrate on choosing your plastic surgeon carefully. Concentrate on appropriate training, certification, and the ability of the plastic surgeon to achieve the results you are looking for. Ask to see lots of examples of his/her work.
2. Have a full discussion and communication regarding your desired goals with your plastic surgeon. This communication will be critical in determining breast implant size/type/profile will most likely help achieve your goals.  In my practice, the use of photographs of “goal” pictures (and breasts that are too big or too small) is very helpful. For example, I have found that the use of know words such as “look the best” or "DD cup” etc means different things to different people and therefore prove unhelpful. Also, as you know, cup size varies depending on him who makes the bra; therefore, discussing desired cup size may also be inaccurate. Again, the use of computer imaging has been very helpful during the communication process, in our practice.
3. Once you feel you have communicated your goals clearly, allow your plastic surgeon to use his/her years of experience/judgment to choose the breast implant size/profile that will best meet your goals. Again, in my practice, this decision is usually made during surgery, after the use of temporary intraoperative sizers.
 Cost of surgery will vary from one practice, and from one geographic area to another. You will find some average cost of surgery listed on this website, and on individual plastic surgeons' websites as well.  
In regards to outcome of the planned procedure, more important than costs of the procedures will be careful selection of your plastic surgeon. I would suggest starting with the American Society of Plastic Surgery and/or the Aesthetic Society of Plastic Surgery to obtain a list of well experienced board-certified plastic surgeons.
Then, I would suggest you visit a few surgeons whose practices concentrate on aesthetic surgery. Ask to see lots of examples of their work and preferably speak/see patients who have had similar procedures done.
Be very careful with your decision-making. You will find, while doing your due diligence, that there are many different “specialties” who will offer their services to you; again, I strongly recommend you concentrate on surgeons certified by the American Board of Plastic Surgery.
I would also suggest that you do not base your selection of plastic surgeon primarily on costs of surgery; keep in mind that revisionary surgery may be more costly in many ways.  
Best wishes for an outcome that you will be very pleased with.

Of course you can get what you desire, and the price you can get from the real self site or a local call to your plastic surgeon as it varies. I recommend an in person consultation with a plastic surgeon to discuss your goals and be measured. After I do this with my patients, we then look at pictures of women with similar measurements with different size breast implants. My patients tell me that this process is very helpful in determining what size breast implant is right for them. 
Dr. Ted Eisenberg, Board Certified Plastic Surgeon and Author

You may find that ultimately you need even more volume than that. You may need a lift on the one breast, and certainly you would need more than one stage to achieve your ultimate goal as there will be an anatomic limit preventing you from getting there in "one shot".