Skull the Slayer only lasted 5 issues, plus MTIO #35 and #36, so that's too short for a trade, so a $7.99 collection would be best.

A Black Goliath trade could include #1-5, Champions #11-13 and MTIO #24. If you want to do 2 Black Goliath/Giant-Man Classics ala Nova Classics, maybe you could then follow up with excerpts from Project Pegasus and MTIO #82-85 ("The Final Fate of Giant-Man").