I got a full set off ebay for about $40, replaced all the heat riser gaskets, checked to see if it need milling and slapped it in.
Also have bought a number of used parts from
http://www.cruiserparts.net/parts/fj60.html
and never had a problem with anything from them. They currently list the parts:
Intake Manifold 81 - 87 No warping/Cracking etc. $150
Exhaust Manifold 81 - 87 No warping/Cracking etc. $150
Intake w/Exhaust 81 - 87 Get both Manifolds fully assembled $250
Have also seen the offy manifold on ebay, but it has been out of production for a long time I think.