Arcane Shot deals (RAP x 0.15 + 492) and costs 5% of base mana.
Steady Shot deals (RAP x 0.10 + 252) and costs 5% of base mana (+175 Dmg to snared targets).
Chimera shot deals (125% weapon damage) and costs 12% of base mana.

Multi-Shot is listed as (an additional 408 damage), and costs 9% of base mana.

9% makes it almost twice as expensive as Arcane/Steady shot, but not sure how damaging against a single target. According to the hunter ability page on wowwiki, it is the 2nd hardest shot behind Aimed Shot (and discounting Kill Shot). So basically twice the mana cost, but hits a single target harder then the others.