Just did a little googling to find out costs
brand new AR-15 Bushmaster $1,700
10 100-round magazines 1,790
1000 rounds of ammunition 1,750 (on sale)
total cost $5,240
Oh, and I should mention about that ammunition
it is SS-109 armor piercing rounds
so you can shoot right through the police car
and right through the policemen's vests
and this is all legal