Well since you cant buy those bases anymore I had to figure out for myself how to make something equivalent. Heres what I did and it worked perfectly.
-Buy a sheet of cork.
-Rip a chunk out in the shape you want. Circular being the obvious choice for most.
-glue smal rocks around the flat area at base. I used woodlandscenics.com Medium Ballast
-Cover medium ballast rocks with globs of varnish to help seal it in a little.
Great tip! For those who need something to try it on and don't want to buy the bases, use corks! Just cut a chunk the height u need, and pick bits of it off with ur fingers or plastic cutters until u like the effect, prime and as above!