Note that when you are paying $1.50 for 250 conscripts as the South, you are actually paying a total of $375 in order to get 130 MORE conscripts than you would if you had paid NOTHING. So, the important number is the extra cash you are paying for the incremental number of conscripts.
From this chart, it becomes apparent that $1.00 is a bad deal. For both sides, you are paying a very high premium for just a few more conscripts. For the South, $150 for 30 conscripts, and the Union is paying $320 for just 50 guys, which is even worse.
The other two options, you are clearly trading cash for conscripts. My gut tells me the South should never go over $1.50, and probably should select "FREE" sometimes, depending on your money situation. There isn't a big win for $2 option on either side, so it's simply a matter of how much cash you have vs. what you need.
TAKEAWAYS:
1. Don't ever pick $1
2. If CASH is a limitation for you, don't ever pay a premium; you get a cadre of conscripts FREE anyway.
3. Understand the total amount you will be paying out, and make sure you have that amount ON HAND (otherwise, you will really be wasting your money, because you'll pay $2 only up to the amount of money you have; that may be throwing it away)

