To answer the original question - This is the way I figure it...
$25 for a pound of powder at 13 grains a load = about $.05/load (I can buy locally)
$40 for 500 bullets = $.08 + shipping, but if you buy other things, the shipping is not so high so $.085/bullet
$30 for primers(if you can get them) + hazmat fee for 5K = $.0345/shot
$25 for 100 cases getting 5 reloads/case = $.05
These are ball park figures, depending on how much you have to pay for your supplies...but I have bought all of these supplies at the price listed, recently.
That adds up to $.2195/shot = $10.98/50 rounds, you can get 22 Mag ammo for that price, but I can not buy the cheap stuff and get any accuracy, so the 22 Mags I shoot cost more like $12 - $14/50 rounds + shipping. If I buy 22 Mags locally there is 7% sales tax and they are much more expensive. Premium 22 Mag ammo costs as much as $19.95/50 + sales tax of $1.40:o - yes ammo has went up in price too. The advantage of the 22 Mag is you do not have to reload for it, just load up the rifle and start shooting. I think it depends on your personal tastes and if you are already reloading. If you need to set up to reload the Hornet, you are much better off going 22 Mag, unless you are going to shoot thousands of rounds a year.
BTW I also shoot 221 Fireball and I can shoot those at about .30/round or $15/50. Same primers, same bullets or a different bullet (50 grain MidSouth @ $45/500), different case, more expensive ($35/100); but last much longer and a little more powder/shot. 16 - 18 grains of it. My Remington 700 in .221 Fireball is extremely accurate and the T/C Contender does not do too bad either (my favorite woodchuck carry gun).