I am a factory-trained technician with more than five decades of experience. All my machines include the tear down and reassembly of each machine which is meticulously cleaned, with full lubrication and reassembled to manufacturer specifications. 

 Superb 1961 OLYMPIA SG-1, CURSIVE/SCRIPT typeface, in near factory fresh condition.  Full refurbishment, NEW PLATEN ($175 at my cost), NEW silk black & red ribbon ($14.95 value), all NEW feed rollers, NEW sound insulation pads and a copy of operators manual.   This machine has an excellent touch and operation.

You can expect prices to continue to rise for the foreseeable future on professionally refurbished machines because of the scarcity of local, factory-trained typewriter repairmen and the machines themselves. Logically, professionally refurbished typewriters will be the better investment long term.

It can be argued that the Olympia SG-1 is the best office typewriter ever made. 

Olympias in general are called the Mercedes Benz of typewriters by those that work on them and I heartily agree.  In my opinion, the best made typewriters in the world are Olympia surpassing even the ultra-popular (and much more expensive) Swiss-made Hermes machines and I work on them both.