vavle springs/engine head related

Okay guys, some of you may know that last week I discovered an engine head gasket problem. I gave the car to the Honda agent in my area (and I tell you, it is a rip off but my brain is relaxed). they just called today to say that the vavle springs are below the allowed limit. This will effect marginally the compression in my pistons.

Anyhow, I have a couple of questions:
1- on average how much to change those vavles
2- can that be done without taking the engine head off (like sometime in the future??)
3- I heard that there are better valve springs around, any advise??

I’m feeling a little bad towards my car this month, it has been sucking my money!