In a word, "meh."
I own five machines today. I owned five before, sold one, owned four for a long time, just bought a fifth.
I'll buy more, too, and have the room for them. But..... only at a price I'm willing to pay. Of course the other side of that is that the seller has to be willing to sell, and at the ridiculously inflated prices I've seen of late, that's going to be a problem.
Or is it?
Not really. If someone is willing to fork up 2, 3, 4x or more what I think a machine is worth, more power to them! It's their money, and that's their call. I won't pay that, but that's because I don't see the value they do. There is no "right" and "wrong" just as there's not for a house, a car, a boat.... or a pinball.
There is only an offer and an acceptance, or not as the case may be.
I have a wad of cash for machines I want to own -- a nice list in fact. But I also have a price associated with each in what I consider to be 'acceptable' condition, and that's 100% working and a certain level of cosmetics. For everything that the machine is not on that list there's a price adjustment -- downward -- because my time is worth something and parts cost money to either buy or fabricate.
This means I pass on a lot of "offers", but that's because IMHO the sellers are insane. Of course that's my opinion, and it's only validated (or not) by others in the market who either agree with me, are willing to pay less... or will meet the ask.
Does this concern me? Not really. It means I have a smaller collection than I'd like, but I've been doing this for close to 20 years, and I frankly don't care about the bubbles. I'll let someone else lay out the cash for NIB, LEs, resales or whatever. When the time comes and they need money, and have a machine they need to dispose of, I've got a wad of cash -- but only a certain amount, and no more.
That's what makes a market.