Many of Dolphin site owners were confused by Akismet pricing. But the things are not bad at all, you are still can use it for free for testing purposes and for productions site you can use $5 plan if you have less than 10K requests per month. Here is official quote from Akismet:
Our starter-level pricing is $5 per month ("Pro" level) and I think that's the appropriate level for any of these networks when they start out. Our basic view is that this level works for most keys unless the number of calls gets out of hand (over 10k a month) in the which case we might ask you to upgrade
