Well, this is a wacky one. I only have $1000 dollars how would I get rid of everyone on the planet.
(this is all hypothetical)
Bribe a Ph.D. student for his access to a genetic-engineering lab, design a deadly virus with long incubation period, release in the nearest international airport.
You will need to know how to design such viruses. If you do not know that, use $1000 to apply to a bunch of Ph.D. programs in bioengineering.
Finally, $1000 is a enough money to get a place to stay for a few weeks, which is enough to find a job, which will earn you more money, which you can use to advance your agenda.