I did a quick search for the Helium 55, which took me to the Bergans website; on their home page, there is a store locator. I found maybe half a dozen shops in the US listed there, mostly in New England; they appeared to be ski shops. I didn’t go to those sites to see if they stock the Helium 55 - but there was contact information for each store; if the store doesn’t stock that model, they might be able to special order it for you.
Although it wasn’t listed on the Bergans site, I did notice that Moosejaw carries two models of Bergans pack (but not the Helium) - again, that might be someplace who could access the pack for you. (Backcountry Gear does not carry Bergans, or at least not that I could find on their website.)
I apologize if I just reinvented your wheel, and I’m sorry I couldn’t be more help.
Might try this again if I make it to New England next year.
The weird part of this ( to me, anyway) is that this was one of the highest rated pieces of lightweight gear about two years ago. I picked mine up on sale, and now can’t buy a second one. The back length adjustment on the bag is solid, I like the zippered opening, and the 55L bag fits my late fall gear wonderfully.
There are some 40L women’s ones on the US market in Campsaver’s bargain bin, but that’s a little small, IMO, for the type of fall backpacking I like to do.