Honestly for Utah road trips you dont wanna mess with manual focus when the light is changing fast. I had the Rokinon 14mm f/2.8 IF ED UMC on a similar trip and missed a few shots because focusing manually on a crop sensor in bright midday sun is brutal through the tiny T7 viewfinder. Grab the Canon EF-S 10-18mm f/4.5-5.6 IS STM instead. Its right around your budget at roughly 250 bucks new and the IS actually saved me when shooting inside slot canyons where tripod space is tight. Plus having that zoom range makes framing landscapes way easier from overcrowded pullouts where you cant just step back. You wont regret having the safety net of autofocus when youre tired from driving all day.

@Reply #2 - good point! Missing shots because of manual focus happens way too fast out there. If you want to stick strictly under 300 bucks and skip the focus headache, the Canon EF-S 10-18mm f/4.5-5.6 IS STM is honestly your best bet for a crop sensor. You get IS and quiet AF, though the aperture is a bit slow. Another solid option if you stretch slightly is the Tokina AT-X 11-16mm f/2.8 Pro DX II used, which gives you that bright constant aperture for night sky shots in Moab.

Re: "Honestly for Utah road trips you dont wanna..." - totally agree with that. Trying to nail manual focus on a crop sensor when the light is changing over Zion or Bryce is a recipe for missing the shot entirely. Over the years, I've tried many wide setups on my older bodies and learned autofocus is a lifesaver out there. Quick couple of questions for you before you buy anything:

• Are you planning to do any low-light astrophotography, or is this strictly daytime landscape work?
• Have you checked the used market for older third-party zooms in that same price range? Let me know and maybe we can narrow it down.