I did some more research today on organic mattresses. There are so many manufacturers who claim to be making all "organic mattresses" that is easy to get confused. I certainly was for about 2 hours today until some additional reading and phone calling cleared up some of the messy mind bog I was in.
I went through the recommendations of The Environmental Working Group that I posted yesterday and also one or two from other chat sites.  There is a pretty wide range of prices (from $259 to $475) and a range of materials. Some are manufactured using a combination of wool (a natural fire retardant) and cotton, others are purely cotton, others are foam or rubber.  One of the issues I need to address is that we suspect that Birch is allergic to wool. We don’t know this for sure but based on the rashes he got from his wool sweater and hat from Ecuador it is a possibility. The other thing to consider is that latex and wool are both considered possible baby allergens. If you have a history of these allergies you might steer clear of these mattress materials. Although it is considered that an allergy to rubber might be from the proteins of the rubber which wouldn’t necessarily affect a child as the rubber is deeply embedded in the core of the crib mattress. The allergy to wool is usually from the harsh chemical treatments used to take the lanolin of the wool out (which the following manufacturers shouldn’t do) so perhaps the wool allergy wouldn’t affect your decision to go with a cotton/wool combination mattress.

Here are the manufacturers that seemed to have the best prices and selection.
Note that the coil comparison can effect pricing (and of course the reputation which is as follows):
Earthsake has 2 crib mattresses, a cotton/wool one called The Cloud ($337) and a 100% cotton one that has a natural flame retardant (which I am still waiting for a call back from them to explain this) that is called Tranquility ($265). Both are 180 coils. This is a basic coil number- not a really firm mattress, in other words.
Naturepedic has 4 crib mattresses. They do a nice comparison of them for you on their site. The No-Compromise Organic Cotton Classic is the basic model which you can choose in either 150 coils ($259) or 252 coils ($299).  The difference with these mattresses is that they are only cotton, the don’t use wool, rubber or latex and they have a flame retardant. The flame retardant is a mixture of silica and baking soda. The problem with this manufacturer is that they wrap the outer surface
in polyethylene which is a synthetic material which is made from
petroleum and is basically the same material as a ziploc bag. So, I
would not recommend this brand.
Ecobaby has a basic organic/wool mattress that is 260 coils ($299) and a natural rubber mattress that is rubber with cotton and wool quilted to the mattress ticking. It also has 260 coils for $399. Ecobaby is on the Green Guide that is put out by National Geographic.
Lifekind sells 2 mattresses. One is made with cotton/wool that is basically a cotton core quilted with wool and then cotton.  The cost is $375 for 280 coils. The other one they sell is a natural core of rubber with cotton and wool, no coils for $425. They can send a sample of the crib material and an allergy kit. (Both are being sent to me). This manufacturer has been in business for a long time and they have 70% of the organic mattress manufacturing market.
Ikea makes a PBDE-free foam mattress with alternative chemicals. Although I thought foam was synthetic so perhaps this is not a truly organic mattress? The prices range from $39.99 to 79.99). I think this is a great, affordable option.

In conclusion, we will either go with Lifekind, Ecobaby or Ikea. Big differences I know, but it makes sense to me to either go for the whole shebang (Lifekind and Ecobaby) or compromise for semi-organic (Ikea.).

Related posts:

1. Organic Mattresses- more research
2. Organic Mattresses- Worth It?
3. Infant Deaths on Air Mattresses
4. Green Baby Furniture