Actually the basing kit from GW is actaully quite good. I won one a while back and was fairley impressed.
If you don't want to go that route, I use sand (as in from a beach its $0) and then fine gravel or slate (the basing kit comes with it) and then static grass. I think BG sells gravel and static grass if not most hobby stores carry it.
I usually use a coat of sand and some rocks, prime, paint and then use the static grass.