Costs vary widely from region to region. These are costs I've experienced recently - Your results may vary:
Plain cylinder boring is usually $8-10 per hole;
Remove cam bearings, Hot tank case and heads, mag check all three pieces, install new freeze plugs and bearings is about $140;
If you need align boring, expect another $80. If you elected to align hone instead, it would be much less, but you would need to use a short timing chain and could experience clearance issues on a stroker with a standard base circle cam. If you change to new main caps (such as splayed 4-bolts) you really should align bore instead of hone;
Balancing the rotating assembly is usually $125. If you aren't going to see a sustained 6,000 RPM you might get by without a balance. If you are changing pistons and rods, you really should balance.
Usually you can get new valves installed in iron heads for about $5/seat. Aluminum heads or those requiring a seat insert would be more;
Any top-side work on the heads, such as spring seat machining, stud boss milling, or guide cutting would cost extra, and I have no clue about the costs since I generally do my own.
EDIT: I errantly wrote "rod caps" where "main caps" should have been...
