So, I've finally decided to pick up an AR and I'm tempted to buy a preban lower. The only issue is I really don't know what to look out for when it comes to used preban lowers. My gut says to go for a colt lower which undoubtedly came from a complete rifle and is a known benchmark when it comes to AR's. What should I be looking to spend? I have come across a few complete lowers in the 650-800 range (colt being on the higher end of the spectrum). I also considered complete colts (~1500) but since I want a flat top rifle I feel like it'd be a waste of money as i'd most likely be going with a new upper anyway. The thing that makes me pause when looking at the colt lowers is the sear block and the larger pin holes. I know they make adapter pins but what about the sear blocks? Will I be able to run a different trigger (giselle and such) if I decide to down the road? Is it really worth it to get a pre ban lower or should I just got grab a ban compliant S&W MP at gander for like $800 and call it a day?