I got a nice heavybag stand recently. It has pegs in the legs for barbell plates, but I'd rather use something cheap. What suggesteth y'all?
I just went with barbell plates. The advantage they have is that when you're not using the bag they can also double as, well, barbell plates. People also use sandbags.
How much weight do you reckon I need? It's an 80 lb bag, and I drill everything from punches and elbows to spinnning back kicks.
I had a bag that was probably around that size - I'm not quite sure how big it is - and I weighed it down with 20kg weights on both of the front supports and 30kg on the back. I only had problems with stability if I let the bag swing too much. This is with punches, open hand strikes, elbows, knees and kicks of all kinds.