I bought the Gila backpack in X-21 and think it cost around $360. The new bag (no frame, harness, or belt) cost $270. If I like it, I'll sell the existing X-21 bag that's on it.
If a friend of mine were to start backpacking and only wanted one backpack, I'd probably suggest they buy the Unaweep 4,800 in Ultra 400 and call it a day. It has a 79L main bag, an 800ci pocket on the front, and gargantuan side pockets. Remove the stays and you're down to 2lbs 12oz and the pack will handle tremendous weight very comfortably. These packs were designed around packing out elk so they can carry heavy loads. This bag could accommodate a multiday adventure.
If someone wanted one backpack for everything, but went on week-long hikes, the Unaweep 6,300 would do everything and serves as a day pack too. My Unaweep 6,300 setup has a main bag that is 103L, 800ci face pocket, and same side pockets. That setup would weigh 3.0lbs in Ultra 400, which is less weight than most people's day bag, and the main bag rolls down into nothing so it is compact.
https://seekoutside.com/lightweight-backpacks/