You are really best going through a local "Benelli stocking dealer", because they can get it quickly and they get great service from Benelli if there is any problem.
BUT, DO NOT MAKE THE MISTAKE OF BUYING AN M4 THAT CAN'T TAKE THE COLLAPSIBLE STOCK!!!
You must buy an M4 law enforcement version (Benelli No. 11707). Any other gun, including any M1014, will not take a collapsible stock. Not the M1014, not the 11701 or 11703. That gun comes with a standard stock and pistol grip. It's about $1200.
Also, you must order the collapsible stock (Benelli No. 70085) as a separate item. It must be installed after you remove the standard stock from the M4. It's about $170.
Finally, get the 2-round mag extension (Benelli No. 81043P). It's about $70.
I know this, because I just got all this in and installed the stock and mag extension, and it is AWESOME!!!
You may want to check with www.calssportingarmory.com
and read the stuff there.