Ive hung lots of drywall, as side work, ceilings, oh man, I don't mind doing walls, even 12' sheets of 5/8s, but I don't do ceilings, that is murder on your arms, shoulders and neck. Ive never used a jack, just scaffolding, (when its over 8'). Personally, I could not right that check quick enough. If I had more than a 30'x30' to do, Id probably buy the jack and do it myself (reluctantly). But at the math you've got, if you don't plan to do anymore ceiling work again, you're time and money ahead to pay for it done, than buy the jack and doing it yourself. Just my 2 cents.
Now for the tape and mud, you know how some people have a natural nack for things ? I'm highly skilled mudder (without years of experience). I don't enjoy it, but don't mind doing it a couple times a year. When I'm done, you have a hard time telling where the seams are.
Good luck!, Bill