Honestly, my son has the $60 Sealy from Toys R Us and it has coils - can't remember the exact name but he LOVES it. It doesn't expel air, it seems super comfy and he's been on it for 3 years know. I personally don't think it's worth it to spend hundreds. Windsorpeak or Baby411 has lots of crib mattress details.
ETA....well, I have to remember that I bought the mattress nearly 4 years ago --- that mattress is now $99 but IIRC I used a coupon. Here it is:
Sorry! Forgot about inflation