Problems with Costings

Hello, I'm new on here so apologies if this has been addressed before! I am struggling with standard business plan templates and I feel sure that there must be a simple answer but I've been unable to find it (numbers are not my strongest point..)

My problem is that my product is a training video, so it costs a lot initially to create it, but it can then of course be sold an infinite amount of times, in theory. Ordinarily a product would cost x amount to make, which would then be marked up by a certain amount to make y, the retail price. In the case of a training video the cost price far exceeds the price I will be selling it for.

My questions are;

1. As I am not marking up a cost price, how do I come to a reasonable retail price for the product?
2. I'm struggling with forecasting how many I will need to sell; some simple software assumes that as the product costs, for example, £2000 and is sold at, for example, £200 that I will clearly be making a massive loss!!

I feel sure this must be a standard business model but as I say, I'm struggling to find any help with it.

Thank you very much in advance for any advice :)