How much is it to register a auto in ma that you bought in ny?

I don't know the exact price, but I can tell you it will be comparatively expensive - New York State charges registration tax on vehicles sold in the state, even if they're not registered in the state of New York. I learned that the hard way in 99, when I was in Virginia, registering a vehicle I'd bought in New York, and it came out to over $400..