Look, the MIC (medieval industrial complex) can be pretty alarmist at times, plus all the big manufacturers of catapults are posers anyway. Seriously, look at the one in the middle there, that's a massive counterweight on what is clearly a tortion-based launch mechanism; what is this, the 3rd century?
Seriously though, I highly recommend making your own, they're surprisingly simple to construct and maintain and it means you can customize the entire system for your needs, again, that centre catapult isn't gonna be throwing anything larger than a juvenile black anywhere further than 100 meters, if you really want to fling a grizzly, you need some serious custom work (a bigger basket for one).
Though I'd recommend a proper trebuchet, nothing can beat the sheer throwing ability of 20m of counterweighted pure POWER.