Cheaper home pinballs have never worked out. $3K will buy a decent "full" game, or a $2K game with a thousand dollars of restoration. Who has space and money for a pinball, but would get a mediocre one—just for that NIB smell?
Vacation America didn't sell. Costco Batman didn't sell. Zizzle isn't making pinballs. Back in the '70s when pinball was king, Mattel, Bally, Wico all tried it, among others. If Bally couldn't do it in 1978, it's laughable to think that Stern could do it now. (I could be wrong about The Pin. But I have never seen one or heard of anybody owning one.)
Stern's success in the last few years has been segmenting the other end of the market, extracting a couple extra grand from collectors who can afford to get the LE. Pure profit, and the people that I know that have those games treasure them.
P2K style playfield swaps have never been a big winner either. (See Gamatron.) I don't think Williams sold many kits. It kind of limits your resale value. I think they discovered nobody wants a loose playfield. Can't sell to casual owners without a cabinet!