yep, you are right about the 3.1 L VR6, $4899 for the crank/pistons/rods etc. but you have to supply the block/heads. here's the link.
http://www.eiptuning.com/enginesandparts/engine%20packages%20VR6.htmladd 3 grand for a complete engine.
http://www.eiptuning.com/enginesandparts/vr62829lcompletemotors.htmlexpect high prices but a high return as well. should be awesome if they work everything out properly.