It's not that expensive… my guess is that if you need a 8 CPU licence Apache would have crashed a long time ago.
Firstly it's 8 phyiscal CPU's, that makes 16 threads on most servers.
A 2 CPU licence will allow you 4 threads and with only 4 threads you can cope with quite alot of visits ! Don't forget PHP and MySQL don't count towards the limit for for most installs a 2 CPU licence will probably be plenty on a server with 8 threads maybe even on 16 thread servers.
We've started with a 4 CPU licence (8 threads) on a server with 32 threads. From the current usage I doubt we will need the 8CPU (16 thread) licence. If we do need it one day then the licence fee will be easily paid for by the extra customers litespeed will allow you to put on the same server.
The crazyness of the 8CPU licence will allow you to host a crazy number of page views !