Those are great sandals and your explanation about why they'll work for you convinces me that they'd have been a smart purchase at almost any price!
I used to suffer from FOMO when I was in wardrobe-building stage. At that time, I really needed pieces to make my wardrobe work and missing out could mean waiting a season or more to wear an outfit.
I also suffered more buyer's remorse in the past. Mostly out of guilt (it was expensive!! think of the environment!) But now I just try to roll with it. If it didn't work out, I gift it to someone who will love it.