Hi yaal,
Thanks for the suggestions. I was just looking at a rough figure so that i could calibrate myself. Which I have-Thanks Erik.
To answer your questions. I am from pakistan. And like in most other countries, contracts are a bad idea if the project if very small. I mean if the guy refuses to pay, I can't litigate anyways, since he is in Australia and I am in pakistan. I dare not even think. Anyways, I trust the guy and in this part of the world that is still worth more than any piece of paper. I am not saying I trust everyone, just that when I do, I think that is most important.
But while we are on the topic. I want to discuss an extension of my problem.

I want to sell a guy a piece of code. The guy is far away, some other part of the world. How do I make the exchange without physically going there. I don't know anyone in that part of the world. I am faced with this problem often so the place keeps changing. Now the problem bieng mutual, that guy has no reason to trust me either so he dos'nt want to pay before he gets the code.