The prices of Queen size Memory Foam mattresses vary greatly. They can sometimes be found on sale for about $300, or their price can get up to about $1000.
Enough to break your neck.
There is actually more than just one one mattress manufacturer that has a memory foam queen sized mattress. But the most noteworthy company is Tempurpedic, which was the first to release this kind of bedding in 1992.
You can find a good quality memory foam mattress out there for around $400.00 to $500.00. The most expensive ones out there are charging you for their fancy advertising. However, beware of cheap imitations as well.
Although memory foam was invented in the 1960s by NASA there is little evidence of health benefits due to sleeping on a memory foam mattress. Those that sleep on such mattresses say that they enjoy it but scientific studies neither support nor deny any health benefits.
You can find more information on memory foam mattress at this site: http://www.memoryfoammattress.org/ and when you are ready to buy Overstock offers shipping for $2.95.
Visco elastic memory foam mattress toppers come in a variety of sizes, such as to fit a single bed. Similarly, they do toppers for double beds, king and queen sizes too.
The truthful answers is: "It's the thickness you are willing to pay for". One manufacturer I know of makes memory foam mattresses in three configurations: The top 2" of the mattress is memory foam, the top 4" is memory foam, and the whole mattress is memory foam. The price varies accordingly. Personal Note: If you can't afford a memory foam mattress, try a memory foam pillow. Awesome, especially if you're a "side sleeper".
There are many memory foam mattress reviews, to be found on the internet. If you do a Google search, you will find plenty of them.
Sealy Memory Foam Mattress reviews can be found on Sealy's official webpage. There are over 4 thousand reviews and Sealy Memory Foam Mattress are rated an average of a 4.2 stars.
A memory foam mattress pad which increases the comfort of a bed can be found or purchased at several outlets including 'Amazon' and another site called 'Target' which specializes in home accessories.
Febreze.
I just bought the 11 inch king size memory foam mattress from Garden Ridge for $399. The box had no manufacturer's name on it and was shipped from China.