It really depends, common stack don't mean that much. Depend what app is doing, how much dependencies it has, with what external services it talks, etc. Also 5k

It really depends, common stack don't mean that much. Depend what app is doing, how much dependencies it has, with what external services it talks, etc. Also 5k, 10k - this would price per day. And then you hire guy/company for day. It depends from app, but it might take some time. Security is not cheap. Disclaimer: worked for such company.