If you're in the market for a WordPress plugin to build interactive cost calculators, Stylish Cost Calculator is a good option. It comes with a no-code drag-and-drop builder, AI-boosted calculator setup, and payment gateway integration with PayPal, Stripe and WooCommerce. The plugin also includes conditional logic, multi-language support and lead generation, so it can be used in many different contexts. The plugin costs $0 for a limited version, $99 per year for Premium, and $249 per year for Agency (up to 25 sites).
Another tool worth considering is FlowCharts.ai, which lets you create and publish smart forms, surveys, decision trees, questionnaires and workflows. It's not a cost calculator per se, but it's got conditional logic and real-time data analysis that can be useful for creating interactive forms that customers fill out to get a price quote. It's available in three tiers: Economy Class (free, limited features), Business Class ($49 per month or $495 per year), and First Class ($99 per month or $995 per year).