The right conversion factor

The first thing that occupies ones mind in a new country is the darned currency conversion factor. How does one decide that an article or service is expensive or cheap. This is a big problem for people from countries like India where one has to down-convert the US dollar to get an estimate of the price in Indian rupees. One USD is approximately 44 Indian rupees. A newly arrived desi goes to the supermarket. He wants to buy a bar of soap. The problem is I have yet to see a bar of soap in a US supermarket. So the only option left to him is a shower gel. He walks up to the shower gel counter and after browsing through unheard of brands zeroes on to something that sounds familiar. An Old Spice shower gel. He opens the lid, takes a whiff and seems satisfied. But his satifaction is short lived. He looks at the price tag and written in bold letters is $4.02. Using his legendary Indian quantitative faculty he does a rough conversion to rupees and finds that its rupees 170. Are you kidding? How can one spend 170 hard earned rupees on a measure of shower gel that probably will last no more than 1.5 months. Back home one could buy a years supply of Cinthol soap for that money. He curses himself silently about not bringing a years supply of Cinthol with him from home. He feels all flushed and hastily puts the bottle back on the shelf. Wake up call dude! If you gonna think this way you will probably go raving mad in a week's time. So, what should be the correct conversion factor? Well the solution my friend is to normalise your US salary to an Indian one. I went about it like this and I warn you this is a very simplistic method. Lets say my Indian salary was X and my US salary was Y. Convert both of them to the same denomination using the prevalent exchange rate and divide the US salary by the Indian salary to get a factor M. For me this turned out to be 8. Now all you have to do is calculate a stinginess factor. Take the difference of the prevalent conversion rate and the calculated factor. Divide the result by 10 and call it D. Now rate your spending habits on a scale of 1 to 10, 1 being very liberal and 10 being very stingy. Call your position on this scale S, the Stinginess Factor. Now, your correct conversion rate C, should be (S-1)xD + M.

R - USD to INR conversion rate
X - Indian Salary
Y - US Salary converted to INR using the prevalent conversion rate R
M - Y/X
D - (R-M)/10
S - Stinginess factor
C - (S-1)xD + M, is the adjusted conversion factor.

This model takes into account the fundamental truths that:
1) Expensiveness is a factor of the value a person attaches to his money
2) The US is NOT India.

This has worked quite well for me so far. And since it is just a number I dont have to think hundred times before spending on a good or on a service. I just use my own conversion factor to determine how much value I attach to the good or service. As always, I am looking for ways to improve this model. So any commenst are welcome.