You need to ask what your requirements are, not how much it is going to cost.

Extension side you get the advantage of recording internal calls. Finding calls if you have no CTI integration is typically much easier on extension side than trunk side (there's more chance you'll know which agent a customer spoke to and search on the extension that agent used (assuming non free seating) than what trunk a call was taken on).

Unfortunately I can't help with costs as I'm more technical but typically trunk side is cheaper when trying to record a larger number of extensions (most sites will have less trunks than extensions) but typically trunk recording requires some sort of CTI integration.

Trunkside is cheaper for larger installations. For 24 phones I would recommend going with station side. As kiwi says you can still find calls if cti is lost and with station side internal calls are also recorded.

When I was born I was so suprised I didn't talk for 18 months

Well of course, if you don't need to record the internal calls an if the telecom trunks are less,  then trunk recording is cost effective.. I asked it related with my other topic... We have extension based recording, and there are lots of problems due to mdf or cabling and also ports on Nice extension cards. And we decided to have a trunk side recording as a backup system beside the extension based recording.  And i try to get an info of cost an approximately for this backup system.  

Thanks anyway.