Alan,

About 50 cents a round if you already have the brass and a bullet mould. IMR 7383 is a very bulky powder that works in most large cased NE's and is $3 a pound. Have had really great sucess with this powder in 470's and 500's.

From a reloading point of view for the first loading:

Primer- $0.03
Brass- $10.00
Powder- $ .45 (based on 44 rounds per pound @ $20 a pound)
Bullets-$ 2.00

$12.48 each for the first firing. $2.48 there after.

Factory ammo is off the radar screen in terms of price and it might not regulate in your gun.

Thats my take on it.

Corbin