What is the customer acquisition cost for a film/audio equipment manufacturer and/or reseller?

That is a very broad question. It completely depends on the channel, the maturity of the brand and the price point (among other factors). There is no answer to this I am afraid. Also some companies' MER (marketing expense ratio) may be defined differently according to their own standards. The best answer for you is that it would be beneficial for you to work out your own CPA - it will guide you far better than any generic data. I would suggest doing a small targeted online campaign, then continually evolving it downwards. Small bets until you get the number you need.