Determining customer's country on what? IP Address?

Introduction

I've a question about something that I think it ca开发者_JAVA技巧n become a little tricky... or maybe not, anyway. Considering I have to implement a web application which allow users to buy things online, I must show listed price, and also make them pay this price, depending on the user's country.

Question

What is the best practice to get this informations?

Possible scenarios

1. Asking user to specify it (But I can't base my prices on that!)
2. Base my price on the IP Address (Is it safe enought? And how?)
3. Any other ideas?

Base it on the customer's billing address or shipping address.

It's one thing if they're just going to say "I'll select the country with the best rate." It's another thing if they actually make a bank account in that country just for a good deal for you. And if they DO have a bank account in the cheap country, then it seems they should be eligible to purchase it as if they were in that country.

You can use the IP to show them an "estimated" price.

Personally, what I would do is have a base price for everyone, and then appropriate taxes, tariffs, and shipping costs depending on the other information. If people are buying internationally they will be used to this.

I would never use the IP Address. The user could be using a Proxy. Amazon is the bigest shop and is based on the Shiping address. I would do the same.

i wouldnt claim to know the best practice for this, but i can tell you conclusively that steam (a game content delivery network) does this based purely on the IP address, if that has any usefulness to you.

Well,

Imho, you should not worry about that.

Your products should have a base currency (like dolar) and from there, if a user wants to buy that product, the user should pay that product in the base currency (dolar). Right?

All the convertion should be made by his bank provider or anything he uses to buy that item.

Or you really really need that requirement?