E-commerce Bad Bot Defense

I run an e-commerce site that is increasingly targeted by automated scripts creating bogus accounts and bogus orders. Even with CAPTCHA challenges in place and an existing Cloudflare setup, the most persistent bots are still slipping through and costing us time, money, and customer trust... (Budget: €30 - €250 EUR, Jobs: API, Bot Development, Cloudflare, JavaScript, PHP, Security, Software Architecture, Web Security)