Steepandcheap.com has MH's "internal frame (plastic sheet I believe)" UL pack in size M and L for $110 plus shipping.
The catch: The sale ends in 7 hours...
Would have seen it days ago if it wasn't listed only in their "Day Hike" section. [A 50L plastic frame pack called the Thruway for day hikes? Steepandcheap workers aren't the most thoughtful IME.]