Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
The same as all the previous releases of OS X I suspect.
Which pricepoint that is for you depends on if you get an edu discount, etc.

Current retail price of Tiger: $129 US
 
Probably the same as the last few releases...$129 for a single license or $199 for a family pack of five licenses in one household. Standard student price is $69.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.