Like Tenrocca I bought a surplus engine from a GMH dealer.
They are still available but a little more expensive then when we bought ours.
see here:
SPECIALS MAY 11
A choice of engines and gearboxes further down on that same page.
Given you may have to rebuild an engine from a wreck I think these surplus engines are good value.
As Tenrocca said, the bits and pieces add up but you get a new engine with a warranty in most cases.