What is the Cheapest AI interview assistant?

 If you only do online interviews once in a while (as average people I guess), what’s the best way to figure out which AI interview assistant is worth it?

I feel like monthly subscriptions don’t make much sense if you’re only going to use it for a few interviews here and there...

Also curious if the pay-as-you-go option is better for occasional use, or if a subscription option is cheaper in the long run...