You can prep for a possible AWB for much less then $3000. If you have that type of budget, I say more power to you and enjoy your purchases. But for those like me, who don't have the funds to spare to pay for 2 completed rifles, there are other options.
I will be picking up 2 AR 15 stripped lowers as soon as the DROS period completes. Those lowers (from entreprise arms), though not complete lowers or fully assembled rifles, will hopefully allow me to pass any AWB and be considered grandfathered in pre-ban. The cost of the lowers (after tax and dros and yadayadayada) come out to about $110 each.