Agreed with others, it's not about cost per round for ultimate accuracy; to the OP, cost per round depends; and equipment costs have to be factored in if you are thinking cost justification. Spread the cost of equipment over the rounds you load, and don't forget to include your time too.
A loaded 338 Lapua certainly costs more per round than 5.56x45; but a single stage press setup vs a setup for high volume loading cost differently. I don't see many 5.56 guys loading 1000 rounds on a single stage. Yes it's do able, but most upgrade equipment.
That said, sourcing components is a big variable. Is the question, what is the cost per round now; or what i paid for my components? Which cartridge? I'm still casting for 38-special, that's like ultimate bullet recycling, right?
Key component sourcing skills still apply, buy in bulk, buy on sale, buy used from friends / estate sales. For center-fire rifle, i don't think you can get under $0.15 per bullet now, new; but many of us will sell partials at less than that. Accuracy? Well,.it goes bang and will hit most targets. Similar story for powder, a huge cost savings going Mil-Surp; but to what purpose? Primers are the killer now. It's going to cost; however, even at the horrendous price of 0.10-0.15 each, it's still less than the bullet and usually the powder too.
I guess what I'm saying is:. Loading for accuracy, $0.85/round+. Most of us are probably between $1-2/round.
Loading for cost effectiveness? Can be done less, highly variable. 223 Can be 0.25/round, hard to get lower.