foam mattress vs. spring mattress

I was wondering what kind of mattress everyone would buy for their crib?
My husband and I went to a safety workshop and they were talking about how great the foam mattress is and now that\'s all he wants to see.
I don\'t want to spend $250 on a mattress just because one person says it\'s better.
I think I will get some opinions from some other moms. to-be out there. Thanks!