Eli,

Basic info here....."your mileage may differ"

Subaru conversion kit parts cost approx. $1500.

Engines can cost as little as $350- and as much as $2500 (depending on your
patience and creativity in the search).   "Normal" price for  a 2.2L
usually is around $600-$800, a 2..5L from $1200-$1700 and a 3.3L  from
$1200-$2000.

If you're nervous about used engines, I've even heard that you can get a
brand spanking new factory short block will cost about $1200 from the
dealer.

Professional conversions start at around $5,000 complete, depending on who
buys the engine and at what price.  A full 3.3L conversion, turn key (you
do nothing) can with AC, cruise control, etc. can cost as much at $10000.
OUCH!  Do it yourself and save big (as usual).

You pays your money and you takes your pick.  Patience wil help you find a
good deal on an engine.

As for weight....the two 4 cyls are only slightly heavier than a
waterboxer, the 3.3L is at least 100lbs more., but, of the six or eight
conversions I've heard of with this engine....noone has complained about
handling.

Warren