Have a look here:
http://forums.mud-club.com/viewtopic.php?t=42697There have been a few similar threads lately.
Really depends if you want a 'make it fit' conversion, or a 'as factory'...
Price wise in short:
Engine usually around the £1000 mark with radiator, intercooler, all the pipework, PAS pipework, fuel filter assembey, air intake etc etc
Gearbox and transfer box (and crossmember) - £500 ish..
The you will also need the 300tdi spec seatbox, transmission tunel, floor panels, exhaust and a few other bits.. so probably another £300 (that is if you go down the 'as factory' route)
In saying that, although you don't always know what your buying... 300Tdi's do often come up on Ebay for very decent money.
If you were serious, I could probably supply all the bits you need.
Then you've just got the fitting costs.
Ian