The problem with renting is that your provider will probably shutdown you, if your scan rate is high. At least that is the problem with large dedicated server hosters.

Funnily, the post inmediately above you (posted a bit later) mentions:

"I had to spend USD15 to run 8 medium EC2 instances for 16 hours to only find 200++ million hosts"

https://news.ycombinator.com/item?id=5406233

and another study was done using EC2 instances:

https://news.ycombinator.com/item?id=5405483