Sounds like grey-market only products, but with some of those prices it is tempting.
It's always a risk to buy grey market electronics because they aren't covered by warranty. I bought my 1st DSLR (not G-M) over 10 years ago and have never had a need to have it serviced, so sure I could have saved a few $$'s and been fine...but what if? The other thing that may affect your product is access to software and firmware updates, as in there may be none available.
Besides the direct import on the grey market, some of these places buy kits at a discount and split the kits up to make their money; products are still new but may be repackaged. I've seen some where it states that no operator's manual is included which I have to assume is because they are not in English or that they are selling the manual separately as well.
They may also be selling refurbished as new, something to look out for.