If you can't find one locally or online, you can order direct from the Escort distributor, Legacy Sports, and have them deliver the shotgun to an FFL holder close to you, who will do the ATF transfer paperwork for a fee. Most gunshops and gunsmiths offer this service.
I was looking for one of their products and couldn't find it, so I ordered through them direct a few days ago. They have been much better on the phone than most places that I have called. Nice folks. Escort shotguns at Legacy sports
You have to have the FFL holder's information handy. Call Legacy and see what they require. I am an FFL holder registered with them as a dealer, so I do not know the particulars of having one sent the way you would need to have it done.
Numbers are 1-800-5-LEGACY or 1-775-828-0555
I've never tried the 800 number but I'm sure it works OK.
Let us know how it goes.