Sleep Better 2-Inch Visco Elastic Memory Foam Mattress Topper, Twin XL $35 @Amazon
I searched but could not find this deal.
This looks like a pretty good deal for a mattress topper that has 4.3 average rating of 425 ratings in amazon.
Although Twin XL is slightly longer than twin, it is about half the price (weird!!). If you need Twin size, buy this and cut off the extra length