Midwest Industries makes some nice light drop in quadrails,
https://www.midwayusa.com/product/2...iece-gen-2-handguard-quad-rail-ar-15-aluminum, for slightly more than the utg, usually in the $124 to $160 price range, depending on what length you need, carbine, mid or rifle. They also offer a drop in with modular rails, so you just have rails where you want them,
https://www.midwayusa.com/product/2...drop-in-modular-rail-handguard-ar-15-aluminum. One thing that I have found in my experience is that the sub $100 rails tend to heavier than the offerings from Midwest Industries.
On the plus side the Midwest Industries drop in rails are basically a no tools required installation and removal, and have the quick detach sling sockets built in. However, you can experience some slop similar to the standard plastic handguards that come on the MP15, just in case that bothers you. This slop can vary from almost nonexistent to irritatingly bothersome depending on the manuafucturer of the upper. They fit pretty snug on my MP15A and MP15 OR carbines, but were just too loose/sloppy on a Bushmaster upper that I have (not so much that they would not work, but it was just irritating). I have found them to be more than adequate for attaching lights and forward grips to my Smith & Wesson and Rock River and PSA carbines.
Troy Industries has some nice drop in rails but are slightly higher than Midwest Industries. Daniel Defense did make some very nice light drop ins. (EZ Car) at a significantly higher price, which had set screws to snug them up and eliminate any slop. I am not sure if they still offer these though.