There is a setting on manage your kindle page. It says "maximum amount to be deducted for conversion". Set it to 0.00.
Although, I should tell you that for wifi models, they will not charge you as they are not delivering it to you via 3G. Some people at mobileread are just retarded and start a thread without finding out details. There are so many that I only laugh at em and move on. I dont judge em as all of 'em cant be technically intelligent, but I know when to move on and I sure you are capable of doing this too.

But, yeah to be safe use that option. I have already done that. Rest assured though, Wifi model does not cost a dime with conversion. Also, there are two email addreses that are used for conversion:
yourname@kindle.com and
yourname@free-kindle.com. I use the second one.
And please update your signature to reflect that you are the proud owner of a Kindle. We are just a few of Indians who have an e reader
--- Updated Post - Automerged ---
Also, just change your billing address to a Valid US address ( a restaurant or a hotel or something). Then use a US proxy to visit Amazon. It works.
What I have done is that I have changed my billing address to a hotel in US. At work, my network tells Amazon that my IP is american. I download books this way (the free ones without paying a ****in' dollar). So, I am betting a US proxy should work.
Do you have a friend living in US?