"Apparatus of Qualish, huh? Hmm. Good condition. Give ya 5,000 GP for the scrap and the magic essence."
"What? But it's one of the finest examples of magical construction known to gnome! Goes underwater, lights up, it's even got heated seats! Gotta be worth at least fifty thousand."
"Why ya sellin' it then, if it's so awesome?"
"... Five thousand you say?"
Which is to say.. if the PCs don't want the thing, who the heck is gonna buy it off 'em? They're notoriously useless, above and beyond the usual junk magic items.. somebody somewhere wants a bundle of twenty +1 longswords, most other things have at least some use. These? You're pretty much only gonna sell them to dedicated collectors of Weird and Stupid Crap Gnomes Made (and yeah, I agree this thing has to be of gnome origin.)