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.