Hi NHdad,
What is the budget range you are comfortable with and what size mattress are you considering?
I personally wouldn’t do either … buying a cheap Serta or wrapping a mattress in polyethylene. The cheap Serta is probably worth less than you pay for it compared to other mattresses in the same price range. While the polyethylene wrap will prevent any VOC’s … the mattress may not have a significant amount of harmful VOC’s in the first place and they will also prevent the mattress from breathing. I would personally prefer to have materials in a mattress that are already “safe” and have been tested for harmful substances or VOC’s in the first place (synthetic or natural or organic).
I would also be aware that “organic” and “safe” are two different issues and there are many non organic mattresses that are completely safe and you have many good options for considerably less than $1500. Post #2 here and the posts and sources of information it links to is a good starting point for those who are researching the conflicting and misleading information concerning “organic” mattresses and mattress safety and who are trying to answer the question of “how safe is safe enough for me?”.
The first thing I would do is decide on which materials you are comfortable or uncomfortable with having in a mattress … and make sure you are clear on why (in either case) … so that you aren’t basing your purchase decisions on the misinformation or “fear tactics” that are so common on the web.
Phoenix