Added: If you need to pick your handguns from what ammo the Big Box sells you are up the creek without a paddle. Period
To me I think this is where the 10MM gains an edge over other less popular "big boy" autos. You can buy full house 10MM fairly readily. Granted not by walking into Cabelas (though I have seen some Buffalo Bore stuff there) but through companies like Underwood. You can also buy "plinking" ammo from S+B and if you watch for sales its not bad at all - I think my last 1000 round order was under $15 a box.
Can I do everything a reloader can? Nope, and probably not by a long shot. BUT I am not left in the cold also if I don't reload.