Ours are killing at at around 70-80 kilo dw.
We run a mix of pedigree saddlebacks, pie train x largewhite/landrace and pie train x saddleback.
The latter x breeds, convert food far better, and grow quicker and to be honest no one ever says oooo those saddelbacks taste so much better. All are fed the same food, on the same system, and I think that has more to do with how they taste than the breed often. As a result, the latter breeds grow to kill weight quicker, taking less feed.
Feed costs us 25p per kilo, and is a tasty mix of wheat, oats, barley, soya, beans etc etc, rather than a grey, dull, pelleted diet.
Bought in weaners cost 1.60 a kilo live weight. So a ten kilo piglet is £16, a twenty kilo piglet is £32. Good value I think.
They are slaughtered and butchered by a master butcher, about 5 mins from my house, at a total cost of £35.
There are very minimal transport costs, a couple of 5-10 min journeys maximum.
I think a lot of pricing comes from where you are and the market you are approaching. I'm in a rural area, and my clientele are normal folk, if I worked in the city or had access to a large upper middle class market i the south, then I'd probably get away with charging more!