How do you get 100 different IPs trivially and cheaply? I suppose we might have different definitions of cheap; 100 EC2 t3.nanos would be a bit out of my price range, but that might be small change for the next person.
For a business (which what I'm thinking in terms of), $500/mo for 100 IP addresses which you can trivially cycle by destroying and creating new virts is well within cost. For an individual, I assume you wouldn't be crawling 24/7, so bring up as many as needed for short bursts. At $0.007/hr, you could bring up 100 from a snapshot/template, use them for a few hours to crawl whatever you need, and it will cost you just over $2.[1] For longer term but smaller needs, just spin up 5-10 for $25-$50/mo cost.
1: 100 * $0.007/hr * 3 hours = $2.10
DO data is cheaper, but not free, and I'm not sure if they charge for changing IP addresses a lot.
Not to mention that in many cases, admins start blocking while up ranges. And due to scraping, lots of sites block popular ip ranges like that of AWS. There are actually forums where people keep updated ranges for the different cloud platforms.
This was a long time ago, and I don't remember what it cost, and there was a limit. It was certainly cheaper than having multiple EC2s just for their IPs though.