i found raileurope, a very expensive site. i wanted to buy eurail pass for italy-france. once i reach rome, and i buy a pass at the airport ( if its possible) and how can i get to paris?
What trips did you want to use your Eurail pass for? Point to point tickets are usually much cheaper. You won't be able to buy a Eurail pass at Rome's airports...and the few spots they will be available for sale will be more costly than what you see on their website.
I also think that flying is a good idea. I like to use whichbudget.com to find flight options.
You can buy a pass from another seller, but I don't think you will find a better price. (But, you could ask a travel agent in your part of the world--there might be some deal I don't know about.)
You may save a bundle by buying regular tickets (but not from Rail Europe, they mark up heavily).
You can't get a pass on the ground in Europe.