I checked the website last night 395 pounds, about 900 dollars.
I bought mine a year or so a go when the rate was more favorable, its going into the disco transfer case to be fitted soon. 
There's 2 different  types one for defender transfer cases and one for the later disco transfer cases; from the man himself;
 
There are 2 types of LT230 ATB, the difference is the spline diameter for the hi/lo hub, to work out which one is required pls see here :
Ashcroft Transmissions
Regards Dave Ashcroft.
cheers simmo