Sorry for laughing, but finding cheap OEM turbo parts will not be cheap
You may be lucky, you may not
Gumtree, ebay, wreckers, some specialist workshops whould be where I would look
You could also put up a "wanted to buy" add here and elsewhere
Good luck with your search
You may need to also get some machine work and/or modifications done for oil lines
I replaced my RB25 GTS-t engine with a RB30 bottom end and a RB25 head, as if I remember correctly we needed a certain block for it to work
Research alot because you are not the first person to do it
Have a look on "Skylines Australia", it is a common mod to use a RB30 bottom end with RB25's
https://www.sau.com.au/forums/forum/8-forced-induction-performance/
Above gets you to a RB30 conversion thread
