one pound of powder = 7000 grains
Depending on brand and type either 5LB or 8lb bottles are cheapest...
brass can be reused several times if not hot loaded so after acquiring it hardly any expense...
I'm averaging 10 reloads or more. I usually anneal the brass every 3-5 reloads.
primers $30-35 @1000..
one time set up fee...die set
the bigger expense and one that varies the most is which bullet you choose.
So to answer your question accurately you have to define your powder bullet and primer used...
After that it's just math. BTW from what I've seen 6.8 SPC brass is pricey so buying reloadable live ammo the first time is often cheaper than buying virgin brass.