I'd echo everyone else - you 'll never get rich doing it, but you'll have greta fun, learn loads and have the bonus of the best pork you've ever tasted
I can't remember the exact costings off the top of my head and the forum's all changed but for a rough calculation
Pigs - £50 each
Food to get to 85Kg liveweight each £150 (approximately, these costs vary hugely !)
Kill & butchery £50 (varies from area to area)
You'll get around 50Kg of pork products from an 85Kg liveweight pig.
You should break even with 2, make a slight profit with 3 (especially if you can find a good,
legal source of supplimentary feeding for cheap or free) I wouldn't go for many more than 6 for your first attempt, smaller numbers are easier to manage and easier to spot problems with
Try, if possible to get all the same sex too
Butchers - most butchers aren't interested in 'home reared' pigs as generally they have too much fat on the carcass for their liking, but then again, I've had butchers tell me they've never seen a carcass that looked as good as mine from a commercial grower - the colour of the meat, the condition of the carcass etc - it all depends how well you raise your pigs and how much learning you do throughout the process.
HTH
Karen