I have a 450 bushy and its a blast to shoot and pretty easy to load for. You can find Hornady factory ammo for a descent price on the interwebs too, about $26/box is what I am seeing.
I also reload for mine and haven't had trouble finding brass and bullets for it. Takes small rifle primers though so those might be an issue getting your hands on right now.
The initial cost to reload is as follows
$45 for 50 casings(Hornady)
$24-$26 for 50 bullets (Hornady 250 FTX)
$20-25 per pound of Lil Gun
$55-75 for Hornady Custom dies
One thing to watch out for with reloading for the 450, it is designed to use the FTX and that is it. So your bullet options are slim. Don't quote me on this, but I think the FTX is offered in 225 GR , 250 GR , 300 GR bullets