Putting aside the issue of foam falsies and the NON-big bust models who strap them on, pose for pictures, take them off and resume their normal lives (which pisses off most big bust girls who have to carry around their implants every minute of every day, and which doubly pisses off most big bust girls when guys can't tell the difference) ...
True the USFDA has no authority in Canada. However, Canadian medicine has even more government involvement than the US. making the odds of finding a "rogue" plastic surgeon rather small (but not impossible I suppose - good luck).
The two American implant companies, Inamed and Mentor, dominate the Canadian breast implant market as well as the US market. Putting all tact aside, you can imagine the type of behind the scenes pressure on the US and Canadian medical establishment emanating from these companies when faced with an alternative implant made from $10 worth of suture string which would directly compete with their liquid filled bags which they have been able to sell for over $1000 a pair!
In regard to P.I.P and EuroSilicone, I believe that both companies already have custom made molds for 1000, 1500, 2000, 2500 and 3000cc implants. These can be used to produce silicone, saline or adjustable implants in any of those sizes. P.I.P also will make double lumin implants where the sealed inner bag is filled with silicone and the adjustable outer bag can be filled with saline.
In regard to "first time" implants, even adjustable ones, there is a finite limit to the amount the breast skin be stretched at one time. Given a DD cup's worth of natural tissue, I would guess that this limit falls in the 600-800cc range depending on skin elasticity.
There is also a limit in regard to the minimum fill to maximum fill ratio of adjustable implants, which is typically less than 2:1. Too little fill and you risk premature implant failure due to the presence of folds in the implant bag, which rub on each other like a piece of paper folded over and over again in the same place.
Combining the skin stretch limit and the adjustable implant minimum fill limit, it is doubtful that even with natural DD cups that you could use adjustable implants any larger than a 1500cc rating, with a 750cc initial fill, for a first surgery. This seems kind of a waste, since custom implants will cost the same amount and involve the same degree of difficulty importing them into North America regardless of their size.
For a first surgery, I would recommend going with inexpensive US made 800cc rated adjustable implants like for example Inamed/McGhan 133FV's. These could be put in filled to 600cc or 800cc or whatever the skin stretch limit will allow. Then over the next few months, these can be overfilled to 1200cc plus.
THEN after the skin has had a chance to acclimate to a 1200cc plus size, you can think about going with 2000cc rated custom adjustable implants the next time around. These could be put in filled to 1600cc or 1800cc or whatever the skin stretch would allow, and then gradually be overfilled to the 2500cc ballpark. This is the approach that many of the big bust models have used.
If your maximum size objective is in the 2000cc range, instead of going with custom made adjustables the second time you can follow Vixen's approach and go with 2000cc permanently sealed implants either saline or silicone. However, this would require that the first set of adjustable implants be overfilled as far as his humanly possible, like to 1400 or 1500cc, to pre-stretch the breast skin. This is possible, but results in a very firm torpedo like appearance once the fill gets past 1200cc or so. Considering that this is a temporary measure lasting for a few months at most, soon to be replaced by soft and squishy 2000cc permanent implants, it's not a big deal.
With a two step approach you'll have some significant size to show for all of the expense and trouble of getting custom implants made!
Here's an ancient picture with my own McGhan adjustable implants filled to about 1200cc. God, It's been so long since my boobs were actually smaller than my head !