Here are some cacti which I bought from an Ebay seller. They're very nice, and come highly recommended. I need to make some 'sabot' bases for them, some rocks and other rough ground. By leaving the cacti 'loose' and using magnets on the sabots, I can vary the look, and the sabots will be easier to store than big bases with lots of cacti.
I now have more cacti than people for my Old West games… I'm not sure what that says!