Buy what you want because you want it. If they ban it down the road, then you have to decide if you will obey the law or not.
But changing your purchasing habits now because of what the antis might do in the future is basically handing them victory in advance.
The "preemptive purchase" option has been ended by universal background checks for us Coloradoans since "off paper" is a prerequisite for preemptive purchases.