This may sound wierd, but it's something I sort of "invented" and I've been dying to share it. I wanted something I could practice Gao style line drills with, but the problem is that like Xing Yi, the drills all involve stepping forward and into your target. That means that a stationary dummy is either going to get knocked over, or that you're only going to be able to perform one or two strikes before you have to step back and re-position yourself.
To overcome this problem, I set an old heavy bag that wieghs about sixty pounds on a line strung between two trees. The line is just a 2" thick rope and the bag is tied loosely enough to slide along it if you hit it hard enough. The rope will get worn and eventually start providing more resistance to your strikes due to the friction.
The hard part is getting the rope taught enough to support the bag. I had to get a friend to help me and we used my car to get the rope as tight as we could. It works very well and I've always thought that a Xing Yi stylist would love practicing thier five element fists with it. You should try it as it's much less expensive than most dummies on the market, and it's particularly geared toward the type of drills you are doing.
If you wanna go super cheap and you don't have a heavy bag already, try stringing up a duffle bag full of old clothing and some sand for wieght. I also use four old pillow cases full of sand for iron palm training and this would work also. (mines too heavy though , about 100 lbs.)
" You must use your Dan Tien, spine, ligaments, tendons, joints, muscles, and chi for power. Your whole body together, not seperate parts. If you don't, you are not practicing Ba Gua Chang, you are practicing Ba Gua Bullsh*t." - Master George Xu