I believe the laminated trigger sear is cheaper to manufacture because the laminations can be stamped and then put together to form the finished part, whereas if made from solid the sear would have to be machined.
This is only my opinion based on what I have read on the internet, so hopefully someone will be along to confirm or deny it (or both more likely, knowing the penchant some members have for creating controversy) soon.
Happy Shooting!! Paul.
"We cannot solve our problems with the same thinking that we used when we created them" - Albert Einstein.