According to the official blog announcement, Increase in price is almost 5 times the current promo price. Here are the new pricing details of Windows 8:

• Windows 8 PRO upgrade edition: $199.99
  For Windows 7, Vista and XP users who want to upgrade to Windows 8 PRO.
• Windows 8 upgrade edition: $119.99
  For Windows 7, Vista and XP users who want Windows 8 basic Edition.
• Windows 8 Pro Pack: $99.99
  This is for the users who have Windows 8 Basic Edition.
• Windows 8 Media Center Pack: $9.99
  It is an upgrade addon for those who already have Windows 8 PRO.

I guess Microsoft is very confident about their sales after selling around 6 million copies of Windows 8 already. Here, the comparison with Apple is evident. I agree that Microsoft gives completely new Operating System while the upgrades of Mac OS X are just like Service packs. Still, I feel that 200$ for upgrading is too much!