What's a 3600? :-?
Lets see:
3100s (I had a few)
$free.99 (had a burnt valve), $250 (back when the 3400 was upwards of $1500, and VERY new), I think I had another one for like $50.
3400s
$100 (It was actually a 2.2L V4, since it was missing a rod in one hole and a piston in another, this was also back when 3400s were in the $1500 area), $200 (was complete), $100 (complete again, from a burned vehicle, ran fine though), $700 (complete w/ waranty)
3500s
$300 + a mount (came from an accident vehicle, that had a broken front cover, water pump was completly broken away, along with a couple tubes for coolant all bent up.)
As you can see there is quite the range to these engines, depending on milage, and where they come from.
The 3500 swap is more involved than the 3400 and requires more custom parts, all of which I will have available soon for purchase. The front mount is basically ready, my laser cutter just seems to have a lot on the go right now. :-? I will be working on other swap parts once I start my new job on Oct 1st.

imp: I currently have the 3400 front mount ready to go.