A lot depends on where you buy your feed, we buy in bulk saving a massive 3 euros per 25 kilos. So our costs per pig would be cheaper.
Dont forget that dead weight is less than live weight, then allow for bones, head, trotters, these are hard to sell.
1 lb of food per month of life up to 5 months, then roughly 2 kilos a day until departure.
All the veggies, fruit and nuts we feed is as an extra. We always feed full pig nut rations per day. I believe the value of "other" feed can be fed at 4k = 1 kilo propriatry feed. Although this should never replace more than 1/4 ration per day. In winter when they need to keep themselves warm as well, I personally would still feed the full amount.
At the end of the day you get out what you put in.