Pretty much nailed it ^ on the very first repsonse.
As to the use of the term "off the books" that caused so many folks to swallow their gum and start hyperventilating, I knew what the guy meant, and never took it as meaning an attempt to circumvent the law.
I often use the term, "off-grid" in the same sense, but wait, I guess that one has negative conotations of being a, "loner,anti-government, anti-technology, home-schooling, White-seperatist,survivalist, militia-member" ?
And, while I appreciate the potential upsides to having legally-acquired,paperless firearms, in this modern era, we're all already on so many data bases and psych profiles (from Google to the government, assuming there's a distinction there), it doesn't much matter.
If anyone is ever on their radar enough that the JBT's show up at your door with a list of serial numbers, they're not leaving without running a metal detector over everything, and they're not going to be persuaded by the popular (and embarrassingly stupid) "lost them in a boat accident" argument.
So, back on point, tell the guy what the Shields are currently going for, and offer him $200, then order a couple extra mags from magazinewarehouse !!