The feasibility of buying 292 million tickets (as you mention) is a key barrier: many lotteries (Powerball included) explicitly and deliberately require that tickets must be bought in person. So, just as a matter of time constraints, you'd need a (nontrivial) army.
Rough ballpark: 300 million combos - let's say you buy 6000 tickets/hour (which I think is actually optimistic probably by a full order of magnitude), for 25 hours a day (assume shifts and magic days), you're still looking at 2,000 person-days.
Rough ballpark: 300 million combos - let's say you buy 6000 tickets/hour (which I think is actually optimistic probably by a full order of magnitude), for 25 hours a day (assume shifts and magic days), you're still looking at 2,000 person-days.