Welcome caro

[Mux213]

Darkstar,

Buying any part for the hachi new from Toyota is very very expensive But there are other options. Also you need to wander whats broken on your diff.

If you have a working rear axle you can recondition it yourself. Depending on what is warn out you can make it as expensive as you want.

Prices I know off (indications)
Rebuilding your LSD unit itself, so new clutchplates and so on costs you about 150 euros in parts.
Replacing ring and pinion if its warn out is around 150 to 200 euros
New wheel bearings you can get around 100 euros for a set

So in theory you could recondition your rear axle for around 400 euros + labour. In practice often you don't need to do all these things to a well maintained rear axle.

Offcourse when you want to go further, or you've really damaged your axle seriously the story changes. A 2-way aftermarket LSD unit (Kaaz, TRD, Cusco) can set you can over 800 euro's if not over 1000. Alternative stronger ring and pinion sets set you back over 300 euros.
But that sorta thing you only need if you want to go racing or drifting proffesionally. Personally I would spend that kinda cash in suspention and only start looking at spending many bucks for your rear axle if you are really serious about drifting or have to much money on your hand.