Hm, first, I´ve never bought chemicals from Asia, but what in particular sounds ridiculous with that?
50 kilo is an small amount, if you want to process it in industrial scale and a tonne are only some more units of this 50 batch.(if I´m right that 1 metric tonne are 1000 kg)
I cannot say, if the method was really the benzo-method, because then, I think, you will to calculate the costs from different routes to it and to look, if it´s sounds true in the style of an industrial company.
If you don´t fear to ship it to your country and the price is playing a less role, just make a poker game and bet on victory.
But you should know, in this case as in cases of investments in stock markets, you can loose all!
Please note, that I have nope experience with foreign chemical buying!!
(And when, buy only one batch, or, tell him, that it would bee very nice from him to send a sample (10kg or so) to you.
You just want to check the properties of the product to know, if you want to make it a longer business contact...)