It's description is not subtle:
> This blacklist has been created for HARDLINERS. It can, and probably will cause collateral damage to innocent users when used to block email.
So if the mailsystem you are trying to reach employs it, is either experiencing spam levels that justify it's use - OR they made a mistake in using it, if this is the sole reason you are being banned.
The first order of business is of course to complain to your hosting provider. Nobody wants spammers on their networks - but if they do: then this is kind of exactly the reason for this list. The policy describes in detail what made it possible for this netblock to end up on the list, that should be enough for them to take action either pre-emptively or by notifying their offending customer, and if neccessary kicking them off the network.
The next thing you can do, instead of paying for whitelisting, ist to contact the mailserver-admin at system you are trying to deliver mail to. This can be a bit of a hassle - seeing that your mailserver just got blocked - but it usually works. The same way systems don't want to receive SPAM they also don't want to overblock, after all they want their users to receive emails as well. If you are the mail admin of a sending system and you're reaching out to the receiving system this is usually a pretty good indicator that you don't want to spam them.
I have had success doing this even at some larger ISPs, where you would expect this to be more difficult.
I very much enjoy these blocklists - simple, transparent. Loads better than the kafkaesk black holes that are the major mail providers who barely care, and who do not give you easy recourse if you are mistakenly blocked.