I don't agree with your cost estimate, but even accepting it there's no way your spending £1800/4-6 weeks on something as small as 500 lines of code and as simp

I don't agree with your cost estimate, but even accepting it there's no way your spending £1800/4-6 weeks on something as small as 500 lines of code and as simple as PCM audio player code. Your description sounds more like the thing an undergraduate might make in a Hackathon.