I think the seller was asking far too much for that SX88. I'm sure it didn't cost anywhere near that much when it was new in 1954, and even used these sets, IMO, shouldn't go for more than a couple hundred bucks as most; in fact, I remember seeing ads for Hallicrafters receivers in old ham radio magazines that had this one selling new for about 10 times less than the opening bid. What's more, I've never seen any Hallicrafters receiver priced that high at a hamfest. I grant you, the SX series was top of the line in amateur receivers in the '50s, but over $4,000 at auction? All I can say is that the winning bidder must have been in a situation where money was no object.
As to Joe Walsh, WB6ACU, well, he would be in a position to pay that much for any kind of ham rig new, let alone used (I saw a picture of his ham shack in a recent issue of one of the amateur radio magazines), but let's face it, most of us are nowhere near that fortunate. Most hams start out on a shoestring budget and many, myself included, began their amateur careers with second- or third-hand gear or borrowed equipment (I was in the third category after I got my first license over 30 years ago, and the two rigs I've had in between were used; my present ham rig was a hamfest prize in 1991--I have never bought a new transceiver in all those years).