To add to the point above: be careful with those super cheap 10-stop ND filters because they often lean really heavy into a nasty blue or purple color cast that is a total pain to fix in Lightroom later. Since your budget is tight at $150, I would suggest looking at the Tiffen 77mm Variable ND Filter if you want to play with water motion without buying five different fixed filters. Its not perfect and you might see some softness at the edges if you push it too far, but Tiffen glass is solid for the price and way better than a no-name plastic kit from a random site. Also, regarding the CPL... it really is a must for Zion. The way the light bounces off the canyon walls and the river water is intense. You might want to consider the Marumi DHG Super Circular PL 77mm as a middle-ground option. Its Japanese glass, very thin so it wont vignette as much on your wide angle shots, and its usually way cheaper than the high-end German brands while performing almost as well. One quick tip tho—make sure you check the filter thread size on your actual lens before buying. If you have the 18-135mm kit lens for your 80D it might be 67mm, not 77mm. Dont make the mistake of buying the wrong size right before your trip! If you have multiple lenses, just buy a filter for the largest one and get a set of Sensei Stepping Ring Kit to make it fit the smaller ones. Honestly saves a ton of cash in the long run.

Ive spent years testing different glass and Zion is a specific beast. Glare on sandstone is a nightmare without a CPL, and honestly, no amount of editing can replicate what a physical polarizer does for light orientation. Since youre on a $150 budget, stay away from those $20 kits. Theyll just ruin your sharpness and give you a weird blue tint. Heres what I recommend to maximize your dollar while keeping the technical quality high:

• Hoya 77mm Fusion One Next Circular Polarizer
• K&F Concept 77mm Nano-X Fixed ND1000 10-Stop ND Filter The Hoya uses professional-grade optical glass that keeps your reds from looking muddy in the canyon. For those smooth water shots in the Narrows, that K&F ND1000 is surprisingly solid for the price because it uses multi-coating to prevent flare. Just make sure to check your lens thread size before buying tho... usually its 67mm or 77mm on the 80D kit lenses. Getting these two separate items is way better than a 10-piece junk set.

Following this thread

What lenses are you actually bringing? Knowing the thread sizes helps, and are you mostly planning on doing long exposures of water or just standard canyon shots?

Noted!