Is breast augmentation an option if I'm on Warfarin for life?

You really have to weigh your risk of developing a clot against the benefit of having a breast augmentation.
Only your hematologist and perhaps hepatologist would know what your risk is for stopping your medication for surgery. Obviously when you require surgery for cancer, for example, then the risk/benefit profile changes and you would stop the Coumadin and risk a clot for the benefit of removing your cancer. 

Hi, thank you for your enquiry. This is an unusual question but very useful to discuss. In my opinion most reputable surgeons would be cautious of undertaking a breast augmentation for purely cosmetic purposes. However being on warfarin would not normally stop a surgeon operating if there was a medically valid reason (for instance after trauma).
The best advice would come from your current doctors (ie the one's that recommended the warfarin in the first place). If you are on it for preventative reasons, sometimes it can be changed for a different blood thinner (one which thins the blood but wears off faster and might be omitted for 24hrs to make surgery less risky). However, if you are on the warfarin for continued treatment this might not be possible.
If you must remain on warfarin only there might be options to perform breast augmentation through fat transfer. This has advantages and disadvantages compared to the traditional silicone implant method, which I won't elaborate on here, but the procedure (if appropriate) is less "invasive" and therefore usually causes less bleeding.
In summary I suggest you speak to your liver doctors or haematologist (whoever monitors your warfarin treatment) and speak to them about whether it can be changed or halted temporarily to allow elective surgery. Keep them informed of any discussion you have with a plastic surgeon.
Best of luck.