I am based in India, how do i buy from the app store using an indian credit card? The app store is saying that my apple id is valid only for US purchases and that I need a US credit card!

You must be within the Country with a Valid Billing Address and Credit Card for that Country to use the iTunes Store of that Country...

So, if you are in India you cannot use the USA Store...

snigdhachavan wrote:

so does this mean i cannot download anything from the app store.. ...

Not the US Store... if you are in India.

snigdhachavan wrote:

... i wanted to buy the Mac OS X Lion... how do i do the purchase?

http://www.apple.com/in/mac/app-store/

You need to access your iTunes account in the iTunes app on your Mac and change the country from the US to India if you meet the previous stated requirements; a abnk card from an Indian bank with a valid Indian billing address.