I have had my 2.2L Subaru conversion for 2 years now and still love it.
To do a really complete conversion will run around $1400 plus the motor
(like Stan said).   The Yahoo Subaruvanagon Group is a great resource for
anyone interested in doing the conversion.   Brian Steele of SmallCar
Performance in Tacoma has quite a bit of experience in these conversions
now and I've heard good things about his work.   I've purchased parts from
him and he's always been pleasant and professional.   SmallCar and Seth
from H&R (in California) both can make a harness for you if you choose not
to do it yourself.   The prices I've heard run around $600.   I've not
heard anything in regard to the quality of the harnesses, but I know both
of them do quality work so I would assume it would be good.   Personally, I
enjoyed doing all the work myself.   You know your vehicle inside and out,
and there is a great sense of achievement when it's finished.
The performance of the Subaru motor has to be experienced.   It's well
beyond what a waterboxer (even a highly tuned one) can achieve, without all
the dependability problems and expense.   The gas mileage in my heavily
loaded Westy is always 20-22mpg whether I drive in the city or on the
highway.  I have to be careful not to do drive 90 mph when traveling on the
highway because these motors just love to go.
I have created a fairly large website about my Westfalia, and about
Vanagons in general.   A good portion of it goes into detail about the
conversion process.   If you are interested, you can view it at:

http://home.earthlink.net/~matsuwesty

I will be attending the F.A.V.O.R. (Florida Association of Vanagon OwneRs)
event at Ft Desoto in Florida this coming Sunday for any of you that happen
to go.   My van will be there to see and I would be happy to answer any
questions you may have about the conversion.   The F.A.V.O.R. event website
is:

http://home.earthlink.net/~clubvanagon

If you would like more information about that event.
I hope this helps.
Matt

"Life is a journey, explore each day and treasure every minute given to you"