What safe mattress did you buy your child?

I need to buy my daughter a full size mattress for her new bed. I am confused as to which one to buy. I am familiar with the issues surrounding mattress chemicals and flame retardants. However, I am unsure on what mattress I should buy. It is all overwhelming.

Also, it seems insane to spend 2K+ on a mattress for a 4-year old. Any help?

What safe mattress did you buy your child?

I went with 100% natural latex (not blended with synthetic latex...the blends are often marketed as "all-natural" or "100% pure latex," so watch out) with wool and organic cotton ticking. I did a ton of research on mattressunderground.net and went with the blue shoal model in medium firmness from spindlemattress.com for my son. It was the cheapest mattress I could find with the specs I wanted. I love the quality, and it is wonderfully comfortable. Another option I looked at was http://www.sleepez.com/latex-mattress-sale.htm.