Yes, make sure you air it out!!
I got mine on overstock.com. IT IS AMAZING. Serta 4"! Mine is a queen and it came with 2 pillows, for $150. I don't think that's bad at all! I'm sure they have twin size, you should check it out! They accept paypal.
They just want you to air out the smell and let it "bounce back" from being in the packaging.
We have the memory foam mattress from Dormia and it's helped my back enormously. We had a regular mattress for years and let me tell you, every morning waking up was excruciating for me with that mattress, I was becoming depressed from all the aching.