Can’t speak to the exchange rate question, but what you really need to figure out is what you need to make. That number can be all over the place depending on the time it takes, how badly you want to get your foot in the door, what the customer can afford, etc.
What I would do:
1) figure out in as much detail as you can what it will take to make the finished product.
2) nail that to a OVERestimated hour total.
3) figure out what you would feel really good about making for that number of hours work (this needs to be a number you would be overjoyed to be doing this all day long for).
4) then take the number from #3 to the prospective customer and tell them this is what you would normally charge, but you will work with them in order to get started. (You need to have a bottom line in mind – a number at which you won’t do it for less).
The reason to do it this way is you don’t lock yourself into a number that won’t support you. The company you’re working with will feel like they’re getting a huge break, they won’t go around telling all their friends you will work for peanuts, and you’ll get busy.
Hope that helps.
– Frank