Options for monitoring for prefix hijacking

I’m needing to do some research and costing for monitoring for prefix hijacks. What are you all using and what are the costs? Do any of these solutions monitor for possible permutations of a subnet, do they only monitor for IPv4 or do they monitor for IPv6 as well? How often are they scanning the internet routing tables and what are the alerts/notifications like?

I’m trying to get an idea of what people are generally doing and which are more popular before I get sales calls and emails from every possible solution. I’d really appreciate honest answers and from people managing large and small numbers of subnets.

Thanks in advance!