My suggestion is to check out parks in your city. If you (or a family member) are a resident of the city, you can usually use an area for a nominal cost ($25-$50), if any.
If you wanted to spend a bit more (I'll throw this out just because you never know what someone is thinking when they say "little" cost), the Desert Botanical Gardens is gorgeous and they have a hilltop ramada area that can accommodate up to 20 people for a ceremony. It's the highest part in the garden and gorgeous. I believe it's $600. I was also told at one point that for small groups with short ceremony plans (like yours), they can work to accommodate trail side ceremonies. Not sure how much that would cost, but couldn't hurt to check it out. The whole park is gorgeous.
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