Hi blackriderx,
Yes … there is more about the different types and blends of latex (including organic Dunlop) in post #6 here.
Yes this is also common in the industry. There is also more about organic certifications in post #2 here.
The only organic certification for latex is GOLS (Global Organic Latex Standard).
Your budget is on the low side if you are looking at either organic Dunlop or 100% natural Talalay unless you are considering a relatively thin mattress with less latex inside it.
Phoenix