How can I tell how much is is going to cost me to train a unit? I can slide the bar but I can't find out where it says how much money it will take. What is it that I'm not catching?
Thanks.

Your best shot is probably looking at "Training and New Equipment" for the current month in the financial report for that firm. However, that updates constantly, so you'll only know how much it costs in a month if you wait for one whole month, or multiply the daily cost (that is, how much said field increases every day) by the days in that month.