Chuckebaby, in post #3 the OP is not talking about second hand versions, but new/unused copies of older versions, ones that can be registered, as he clearly states.
Sometimes you can find those old versions in netshops, but you can also get cheated if you buy from other than a known, reliable company.
Buying a new one is the recommendable way, though.
However, if the budget is limited, one doesn't have to buy Producer. X1 Essential or Music Creator might do for starters. They are powerful tools, both.