M&P slide

Hello all, I am a brand new member to the forum and am looking to purchase a slide mounted red dot sight. I am using the Smith&Wesson M&P line of pistols and am not looking to change brands at the moment. I have a generation 1 4.25 inch 9X19 that I bought secondhand. With the proliferation of hanguns with a mounted red dot, I wanted to learn a little bit more about them. My uses would be mostly hobby/training/competition and possibly home defense once I'm more comfortable with both dot and pistol. I am pretty set on using Holosun based on Sage Dynamics ongoing reviews of his testing procedures. I am looking at Atei for the milling work because I do not necessarily want to have a fully machined slide with features I'm not looking for. In this forum I searched for selling or buying but I may not be looking in the correct place. Could someone point me to the correct thread or does someone have a new or used slide they'd be willing to sell me? Thanks for your input.