Old computers are not like old sports cars or even old bottles of wine. And didn't the C64 have more then 4 colours? I wouldn't pay $12 for that.
Correction: Old PCs
There's a Reason C=One is coming about, old Amigas are still nice, and so are Ataris (well kinda). They lack horsepower for sure, but they have their place in the hearts of those who appreciate them (I would never buy 400 year old wine, I'd certainly not appreciate it)