I got my engine/loom/ECU package for $1500. I did the whole conversion myself bar the exhaust and intercooler setup (which i got at a steal for $150 s/h) and it ended up costing me another $3000. That sounds like alot, and to be honest i'm at a loss to say where all that money went- there were quite a few little mods that needed to be done to get it all going properly.
The part that caused me most problems was the alternator bracket. The original is mounted too low and hits the sway bar on the Sprinter. I went to bunnings and got some metal which i then got welded up at a fabricators, then made up a top bracket/arm from odd parts i had lying around. This really isn't ideal as it's hard to get enough tension and isn't lined up perfectly. Have a look at Sam Q's very sturdy looking bracket in his buildup thread.