I recommend saving yourself some money and buying one of the new texture paints from Games Workshop. Basically, they're paints mixed with grit that yo can use to add texture to your bases. It's available in a range of colours but it doesn't really matter which colour you get as you can paint over it.
I can provide a pic of a base I created using this method today:
I added a second coat of texture paint once the first had fully dried (I find multiple layers much more effective than just the one) and then painted it brown. After that, I drybrushed it a few lighter shades of brown and added some polystyrene rocks and shrubbery.
Hope that helps.
That's not saving money in my books... I slap some pva (white) glue onto the base, this can be watered down a bit. Then I dip the base in some sand, any sand will do. (I have some variety of size in my sand, and I specifically place larger chunks on before hand if I want certain larger pieces in specific places.) I leave this to dry over night and then prime my figures. The spray helps seal in the sand. Then I paint the base a dark brown, and highlight it up with various lighter brown drybrushes. (I don't use GW paints for this as craft paints work just fine, and cost a lot less). Once the paint is dry, add a few dots of pva and add some static grass. Done! 
This way is super cheap: the sand is free, pva is cheap, as is craft paint, and static grass lasts a long time if all you're using it for is bases.
