It's not on Dave to sort out legit sale offers. If anybody has had a bad experience with this seller (eg, sent $ and received nothing), I think it would be OK to post a warning, although I know in general the guideline (in Green Pages anyway) is to post positive feedback only -- and let the lack of positive feedback serve as a negative review.
Those trees won't grow to fruiting size here, but they do look cool.
Word of caution -- be sure to get paperwork in order. I think there's some sort of "small lot" seed permit that you should be able to use instead of going through the effort/expense of a phytosanitary certificate. If you don't have it, though, and customs inspects the package, it WILL be confiscated. I also read in another forum that seeds that sprout along the way may be considered "plants" rather than "seeds" and will also be confiscated. (Fresh seeds from Borneo seem likely to sprout during transit.) So it's sort of a gamble, but one that might be worth trying, if these are plants you really want to try.