We love the wool and cotton futon we got from Small Wonders just over a year ago. I've used others from them in the past as well. It's not cheap, but at the same time, looks to be a lot cheaper than the organic options you're listing here of more-standard type mattresses. Just be aware that, like all mattresses, they are required to be treated with fire retardant to withstand federal flame-resistance regulations (Small Wonders uses boric acid powder on the inner layers, for this). So do ask very specifically about what those organic mattresses are treated with for fire resistance, if part of your goal is to avoid certain chemicals.
The only way around the fire retardant treatment is to get a prescription from your doctor (some naturopaths will do this on request without any fuss) that the manufacturer keeps on file. Our futon has a huge disclaimer tag noting that it was custom made and has no fire retardant and should not be resold. That's ok by us, and we feel really good about sleeping on it.
