Do not pay for a dunning tool yet
At this stage you have a handful of failed payments a month. Free Stripe Smart Retries recovers the soft declines, and the few hard declines you get are not worth a monthly subscription to chase. Turn Smart Retries on, ship your product, and revisit this when you have real recurring revenue.
We make a paid tool, and we will still tell you: under about $1,000 MRR, free Smart Retries is genuinely enough. Come back when you have something to protect.