The minimum announcable IP space is a /24. So you could either rent or buy a /24. Renting a /24 is currently at around $100-200/month while buying is around $10-15k. You can take that subnet to a provider with a "BYOIP" service.
For example, you could set up a company to hold the actual /24 and then have 253 shares in the company, and each shareholder gets traffic forwarded for one IP address.
I'd buy a share or two.
With more cost and complexity, that /254 could be anycasted to avoid it being single-homed too.
How is this going to be competetive? You can get a Elastic IP from AWS for $3.50 per month when not in use, $0 when in use, and the cheapest EC2 instance is $3/month. And there'd be no $50 upfront cost per IP.
Perfect scenario for a blockchain