Lambo,
I've just done the conversion to my R32 GTS25, you can buy the hubs complete, from SSS or Just Jap in Sydney... they are a straight forward swap over, the only problem is they cut the brake lines so I had to buy replacement lines for the rear, at $150... but you could get a locally made set of lines for about $60 if you didn't mind them not being perfect.
I swapped the diff over at the same time (to go to LSD) and the parts cost $2000 from SSS
That included:
4 x GTSt "Type M" Hubs
GTSt Viscous LSD
Half Shafts for new diff
If you didn't want the diff, it would cost btw $1000 - $1500
You're looking at about 6 hours labour to get it swapped over