One can get a reasonable code audit performed on the @SeedSigner firmware with 2 FTEs for somewhere between 2 and 3 months, that is from 1000 to 1250 hours. The going rate for US-based firmware engineering firm for a small project like this is between $150 and $200/hour. I swag it should cost between $150,000 and $250,000 to audit the code and produce a report for seedsigner.