you probably won't like the real answers, but since you asked here you go ...
Yes, Silicone implants ARE available again in the USA. However, the deal isn't the same as the good old days of Dow Corning. Silicone implants can only be used by plastic surgeons participating in a documented FDA study (guess only one doctor in 10 is participating in this study). Also, the largest available FDA approved Silicone implant is rated something like 675cc (resulting in maybe a 3 cup size increase over the girl's natural size).
Nobody in the USA currently makes custom silicone implants, or custom saline implants either for that matter. The reason for this is that the FDA now requires a 'device approval', meaning that every different size and style of implant from every company must be individually submitted for testing and approval at a considerable cost. Because custom implants would need to be individually submitted for every set of implants produced, the total cost for just one set of implants would be astronomical. With a standard sized implant listed in a catalog, the implant company can submit one implant of a particular size and style for testing and approval, pay the cost once, but then sell 10,000 more pairs of the exact same implants once they receive the approval. This new FDA 'device approval' requirement is the same thing that killed string implants, since no two string implants are ever exactly the same.
There are two companies overseas that do make larger silicone implants. However these are not FDA approved and therefore cannot be used in any hospital or clinic in the USA even if you were to buy them and bring them into the country.