I am a huge fan of Swampfox red dots. They aren’t the cheapest, but some models can be had for under $200 and I find them much more robust than many others in that price range as they’re aluminum and also have the option of adding an “Ironsides” which is an additional metal jacket to further protect the sight. Allegedly, many of their optics are designed by a gentleman that designed for Primary Arms. The only downside is that they are made in China; some will slander the brand on that basis alone, but I have not experienced any quality control issues.
Additionally, I was in the market for a Shield footprint red dot sight about a year ago. The SIG Romeo 0, Shield, and Swampfox Sentinel were the only options that had that footprint. The SIG was made of plastic. The Shield had a plastic model which was affordable, but had a metal model which was $350ish if memory serves correctly. For about $250, I got a Sentinel which was metal and works great. I am not criticizing plastics/polymers and I am certain that they work fine in most instances, but I just have more confidence in a metal sight especially one that will get battered around on a pistol slide.