How did Pat Buchanan and Harry Browne do it in 2000? They only got 9k and 6.6k votes respectively, but they managed to get over 50k signatures?
A lot of people will sign the petition even though they don't plan on voting for the candidate (they just think the candidate should be able to be on the ballot). As to how they had enough resources to gather enough, they had paid petition gatherers. Barr's trying to raise enough money to get some as well, but it's in doubt whether they'll be able to make it on at this point.