I have used this stuff myself. The result it gives is, I would say, ebonised. By that I mean it fills the grain with a few coats and therefore resembles ebonised lacquer, in the chinesey, antiquey sort of way, which is the quality that the first reviewer on the Axi site is complaining about. It is sold as ebonising lacquer, and therefore it does do what it's supposed to. However, if you want to be able to see the grain, this is the wrong product.
As to the cheapest place to buy it in terms of postage, I have no idea I'm afraid. Probably Axminster to be honest. Orders under £30 are £2.95 and orders over £30 are free. Turners Retreat also stock it, and they're free over £50.