Hi,
I currently have a 2 inch thick mattress topper made from that memory foam stuff - Tempur I think is a specific brand name for the same product/technology.
I first found it so incredibly comfortable - to the extent the first night I remember not waking up in time as it was so comfy! - I've now gotten used to it and the effect isn't as pronounced, however it's still very comfy.
I'm looking to try and get one of those big 10inch complete memory foam mattresses and I want the pillows as well. I got the topper a few years ago from Costco for around £120 and only place so far i've seen that do these things individually is sellers on Ebay. A local bed shop would do me a mattress on it's own, but the price was significantly higher, only way cheaper was to buy a new bed, which I already have.
I found that theres also a mattress which has normal foam and then a layer of memory effect foam on top, these are cheaper of course than a full memory effect mattress, but comparing to one, I think I still want to get the full memory effect mattress.
Do a little research for what suits you, currently I've only seen 'choice' from sellers on ebay. let us know here if you find something!
Cheers! DtM! West London & Slough UK!