Just discovered this site recently and am very impressed.
I have used a 3/4 length standard thermarest which i bought several years ago and it really kills my back. I recently bought the thickest kathmandu self inflating mat and it is fantastic. It is about 5cm thick and very comfortable. Its great for camping out of a seakayak but quite bulky and over a kilo. I got it on sale for about $70.
I am getting a friend to get me a neoair in america. I tried to get one online but they will not send to Australia. The cost in Australian stores is $309 for the large and is $169 in the US. It is very frustrating that a lot of outdoor gear is nearly double the cost in Australia!!!
John