$189 US for a 1992 Model M?? (plus $44.70 shipping to Canada!)
That's insane. I paid $4 for a 1991 Model M in the same condition. (possibly better condition)
You paid $4 for a professionally cleaned, refurbished, and bolt modded Model M?
I paid $4 for a Model M that was spotlessly clean (I disassembled to check), needed no work and had no broken rivets. I'd actually consider that better than "refurbished".
It's all up to opinion. There was a lot of time and effort put into the listed keyboard. The bolt mod supposedly makes them feel sturdier (it definitely does if the board had missing rivets). The bolt mod also ensures that it won't ever have the be serviced because of broken rivets, and not much else goes wrong with an M.
It's not worth $189 to you, but it might be to someone else. Look at clickykeyboards.com. They have ordinary Model Ms for $95. That's more than Unicomp, just because they are clean and assured working. If a cleaning is worth $91 ($95 - your $4 purchase), why wouldn't a bolt mod be worth $100?
Obviously, $91 is high for a cleaning, but the more reasonable price of $65 ($95 - $30, still decent price for an M), is still quite a lot. A bolt mod requires a lot more effort than a cleaning and if done for you, it removes the possibility that you could mess it up, plus you don't have to spend a few hours to do it.
Why do you pay a contractor to spiff up your house? Why do you pay a repair shop to fix you car/computer/or other gadget? Why do people pay for cleaning services for their homes? Time, effort, and skill. If you don't have the time/effort/skills to do a job, you pay someone else to do it.
