I was in the same boat recently and decided to buy an AR after I looked at the selection of once fired(mostly) brass my local range has to offer in front of the firing line. before i was even dead set, I was picking up brass. I was able to find over a thousand 223 brass in just under an hour, but found two measley pieces of x39. plus, an AR is the S-10 of the gun world, there are so many options for customization, caliber swaps, etc etc.
in my very short experience reloading rifle, it is much more time consuming and expensive than pistol. tumble, sort, lube, decap and size, tumble, trim, chamfer and deburr, prime, charge, seat bullet. $3.40 to reload a 20rd box of 223 sounds like a great deal to most people, but im used to my $1.20/50rd 38, 380, 9mm ammo that takes 1/5th the time to load as 223