You've spent enough on your trailer. Don't cheap out on the chocks and get just one.
One thing to think about with X-chocks is access to them, especially when it's wet and raining out. If you have a slide over the wheels, it can be a pain to mount and tighten them after the slide is out. There's different designs of them. The type that you have to lock with your foot would not work very well in this case.
Another thing with the type that has a nut or handle on the top, in some cases, the wheel skirting can obscure the nut and you need to tighten it by feel and be crouched over. That's what ours is like (BAL) and it's a bit of a nuisance.
In either case, the Ultra-Fab "Ultra Chock" would be much better because it has a lever on the bottom.
Ultra ChockIf you have X-chocks, also carry a set of chocks for under the tires. Once in a while you'll have a need to prevent your trailer from rolling away. As said, for safety, don't use X-chocks for this.