I am cross training from bjj to muay thai and i need to practice my strikes, more than i can at my martial arts school. I looked into a wavemaster and a bob but i read some bad reviews of it moving all over the place. I cant have a heavy bag in my house since theres no place to put it. I have room in my backyard though. Anyone have ideas? I thought of building my own, maybe buy a pole or a log and cement it in the ground 3-4 feet under. Then wrap it with foam and then sand for the outter portion. Has anyone tried to construct thier own and had any luck? I dont really want to spend more than 600 or so total.

With $600 dollars you can buy a good solution. Do more research.