We did pretty much the same. Had 3 weaners, and similar costings over the summer.
However, about half of the butcher cost was for making sausages and bacon/ham, so if you're not bothered about sausages, you can cut £100 off the bill.
I think ours worked out at about £3.50 per kg.
Rare breed pork sells for about £8/kg round here, and the average cost at supermarket seems to be about £5/kg, so I was pretty happy having a good amount of meat for cheaper than Tesco!
Tastes better as well
3 weaners: £135 (They were already a bit older)
feed: £200
Slaughter+Butcher: £355
Total cost: £690
We sold a couple of half pig for £120 as well, then have the rest in the freezer
(2 pigs is about the limit in a chest freezer).
Getting our new pigs (3 gilts to raise for breeding) on Saturday, and can't wait