That's a tough call. IMO pieces of equipment are just like people; everything ages, some more than others. While one individual of a certain vintage may be in poor shape, another may be perfectly fine. I once knew a man that at 87 could work men half his age "into the shade". What he was capable of doing would most certainly hospitalize, if not kill; most men that old.
We have a Skutt KS 1227 here from the 70's that was given to us; it's old and beat up but it does work. We used it as an overflow/backup kiln for our production runs and it worked great despite having been put through several firings and being beaten to death by it's previous owner. We got this kiln when we where just stating out. I haven't seen it in years and while it "worked great when last used" (sound familiar?), I couldn't tell you for sure it would go to temp if I pulled it out and fired it again today.
It all comes down to how well it was taken care of, used, stored and what it's like now. My biggest problem with the one you are looking at iis the price. The guy wanted $500 for our "free" kiln and that just wasn't going to happen. (He was a friend of my father and just needed it and all of his molds out of the way so we more or less inherited it)
I have the same kiln here as you're looking at but most likely newer (serial # 80484). It was stored in an outdoor screened enclosure next to a body of brackish water. The hinge had to be beat to close (stored open), switches frozen to the point the shafts broke before they would turn (but the sitter switch still works freely). It most likely "worked great" when it was last used too...
Is it worth $375? (I wouldn't have given $3.75)
Is the one you're looking at worth $375?
I dunno; can you show me an 87 y.o man who can swing a 45# chainsaw in 96 degree heat and humidity for two weeks straight with a smile and joke the whole time? (In WWII, he literally wore one M1 Garand out dropping Nazis and was well on his way to wearing out a second. He was a man if there ever was one. He was also *the* best, most loving, kind and gentle man I ever knew.)
If you know of such a gentlemen, I would love to buy him a beer....but chances are he aint ev'r had a drop in his life.
It all comes down to what kinda shape it's really in. In a worse case, are you willing to pop for $50 each for new switches if they need to be replaced? Why were the elements changed? Was this due to verified wear or were they chasing a problem? I've seen folks throw money at a problem not knowing the difference. It may need something else, so I would factor that in when considering price. It can be made to work if it doesn't, and like Neil said, it's just a matter of; is it worth doing so to you in the end? I've also seen folks greatly underestimate number of firings too. "Four firings" could easily be, and most likely is; 40.
The only thing I can tell you with 100% certainty is; you never wanted to be on the business end of "Mr. Smith's" Garand...EVER!...
(I've have a great story of him with a 30 caliber Browning machine gun while in basic training.)