In midwest summer conditions and short trips, easy and inexpensive:
If at low altitude/balmy locale, nix sleeping bag.
If out of bug season, nix bug shelter/repellent.
If forecast favorable, nix shelter/rain gear.
In many cases, nix cook kit.
If plenty of water on route, nix treatment and carrying capacity.
Price for weight loss generally goes up as challenges increase and one cannot afford to skimp on certain "essentials." It is quite simple to go SUL on a midwest summer overnight with a just a pad, bivy, pack, dinner, breakfast, and water and clothing worn plus sundries. Elevation, seasons, length of trip, bear regulations, and other considerations increase the cost of SUL substantially, as to "afford" proper rain gear or shelter one might have to switch to cuben, or to cope with colder conditions one must bring more insulation. With my current gear and budget I could not hope to be happy (survivable vs. happy, note difference) on a weeklong SUL trip at 10K' with lows in the 20s (F); I would need to upgrade several major gear pieces to lighter and more expensive options.
I'll let the mountain folks, and those who have put more expensive gear and fabrics into the equation, speak from here.