What he said^^^
Hornady or Hunting Shack, premium ammo with 750 gr Amax, is about $7-8/shot as I recall.
Although I would never shoot 150 rounds of 50 BMG a day. Catshooter lives on a different planet than most of us and has many resources. I can see shooting 20-40 rounds on a typical day at range. Dragging 50 BMG out with my AR15, and another target rifle of sorts, having fun with all at different distances. But still, if paying $7-8/shot, will sting quite a bit.
Many folks buy the $250 Lee 50 BMG reloading kit. Tons of options on projectiles that are more affordable than the Amax, which are $2/each. Some pulled, varying types of ball, API, etc. I've heard lots of talk about South African 690 gr ball, from Wideners perhaps. Read just the other day on FCSA about some bulk powder, 872 perhaps, at Pats Reloading for $48/8 lb jug. Compare that to $140-160 jug for Reloder 50 or H50BMG.
Lake City brass, once fired and polished, is 45 cents each from guy I bought my Barrett IMI cases from. Might be cheaper elsewhere. CCI primers from Powder Valley are much more affordable than the RWS primers I bought from TenX. Depends on your goals, but 50 BMG components don't have to be terribly expensive.
Making high quality 50 BMG ammo for $1.50-2/shot should be very doable. Just guessing as I don't know exactly what those projectiles cost. My reloads are going to be about $3.50/each, but I have a specific goal in mind. Point being, you can reload 50 BMG quite affordably, relatively speaking of course.
Dan