I paid $200 for my old Miller TB AC/DC about 8 years ago, but it did come with about 30 feet of ground lead and 50 feet of stinger lead of copper wire about the size of my finger. The case was in need of a paint job, but I found out that the Ford blue sold at Tractor Supply stores was a very close match to the Miller blue and repainted it.
Even though they are built like tanks, you do need to be a bit careful to test these old AC/DC machines before you buy. I always though mine was a little weak on DC, so I finally pulled out the scope and looked at the DC output waveform. Sure enough, one of the 4 diodes in the output rectifier was blown, so I was only getting half the wave and half the power. I bought a new diode and replaced it, which is pretty easy to do. It welds much better with the full rectified wave on DC.
The difference in wave forms with and without the blown diode replaced basically looked like this: