Hi Shazb0t,
Thanks for the update … I appreciate it
I’m not sure what type of topper material you are most interested in but the lowest cost foam topper would be polyfoam. Post #2 here and the topper guidelines it links to should be helpful and also includes a link to the component post that lists the better sources I’m aware of for all the most common types of toppers (including latex if you wish to stick with the same material as you have in your mattress).
Phoenix