Onyx's license agreement is pretty strict, I don't think it matters if you're in the US or not - they don't want you reselling any models created with their product.
Makes sense when you think about it...anyway these days there's a lot more competition, xfrog and some others, plus guys like you who are making top-notch trees basically from scratch.
But like I was saying earlier, it still seems hard to find fruit trees. Not just citrus but stuff like apple and pear trees...and now that I think about it, flowering trees don't seem to be very common either.
So Lightning, maybe you've got a potential niche there! Get cracking on some fruit trees!