There seems to be some misinformation getting passed around about seed vaults, what they are, who runs them, and for what purposes. There are the small seed collections being offered for sale to consumers and then there are the large true seed vaults being used for storage of genetic material for research. It goes without saying that there is no "ultimate seed bank for any situation" for sale. As with all things, situational context is needed, and caveat emptor, "buyer beware", always applies. Of course these can be labeled as "scams".
Then there are the large seed banks being constructed by scientists in various locations throughout the world. It should be noted that the majority of the germplasm lines (varieties) that will ever end up in these vaults are already stored somewhere. The world's agronomists essentially have a shared network of facilities which house these seeds and they are offered for sale for legitimate research to scientists anywhere on earth. They are not all genetically modified, the vast majority are actually non-agricultural varieties and species, and are weedy ancestors or relatives. Scientists are storing these germplasm lines to conserve the genetic diversity of crops and their relatives currently available on the planet. When a new variety of a crop is developed, plant breeders can use these seeds to breed in traits which would have been retained by this genetic conservation program. This program has nothing to do with normal purchases of seeds by consumers, you cannot buy these seeds if you are not a legitimate researcher. Scientists are not necessarily preparing for the end of the world, or seeking to only preserve the genetically modified varieties of crops, and they are not conspiring to sell you only genetically modified crops. If there is any project which will allow us to reduce the usage of GM crops, it is this one!! There are literally millions of varieties of both crops and "weeds" whose germplasms have been stored in multiple locations, and there are hundreds of thousands for wheat alone. Your heirloom and open pollinating crops, as well and their related weedy ancestors and relatives, are most certainly among those being stored. But it is wise to create your own seed vault, their seeds are for their research and development only. In my opinion, it would be extraordinarily unlikely that these lines would ever be distributed to the public in the event of any type of catastrophic event, no matter the severity.
EDIT: It should also be noted that conventionally bred non-local varieties are just as threatening to biodiversity, if not more so, than genetically modified varieties. Scientists are attempting to conserve the genetic diversity of crops to prepare for increased pest pressures, altered climatic conditions, and desired increased yields. When a local variety of a crop (or even a local weedy ancestor) is lost to a non-local variety, and no seeds from the local variety are kept, a loss of genetic diversity has just occurred. It doesn't matter if the crop is replaced with a genetically modified line or not, what matters is that the original local genetic strain has been lost. That being said, genetically modified crops do have significant ecological impacts that set them apart from their conventionally bred counterparts, the worst of which (with the greatest potential for long term disturbance) is the introduction of transgenes into crop-weedy ancestor F1 hybrids, and into the subsequent backcrosses to both the crop and the weedy ancestor. Once a transgene escapes into the wild, it cannot be recovered. These hybrids act as gene pools and can aid the contamination of a further geographic spread, affecting both natural ecosystems and agroecosystems.