Consider this: Your newborn will spend more time asleep (14-15 hours) than awake during the first year. One of the best investments you can make is to buy a supportive and safe crib mattress.
I researched brands for a Babble.com article. Through my research I learned the key things to look for are support and air circulation. What I came up with was a good all around model in the Colgate Classica. The organic mattress I found, the OMI was more than $400--a lot of cash. Is it worth the investment? Maybe so. The mattress is right next to baby's skin for hours and hours.
On the Giggle site here's how they sum it up: "Rest easy knowing your baby isn't being exposed to unnecessary synthetic chemicals." Hmmmm. Maybe my money is better spent on this than a fancy crib.
If you've got an unlimited budget, I'd also recommend looking into a Natural Mat this brand comes to the US via the UK. They've developed an entirely natural, organic crib mattress, They use lambswool, natural rubber latex foam, coir (coconut fibers), mohair and cotton. I was sent a small (5"x 5") cutaway sample of the Coco mat and must say I'm intrigued. It certainly looks breathable and supportive. $374.99 (right now there is a 5% savings at exclusivelychildrens.com)
Organic or not, it's a good idea to read up on crib safety before making this purchase. The National Safety Council has a solid list. Sweet dreams!