Are they worth anything? We’ve got a couple of C64s in the attic, and I’ve thought about selling them. I think one works, and the other could be spare parts...
They're worth a little bit to collectors of such things, but that's about all. After a collector gets an armload of them they don't want any more. If someone offered me another C64 system at this point for $20 I wouldn't pay it. One day about 11 or 12 years ago I took the trash out to the dumpster and found a complete Atari 800 system in the dumpster. I dug it out and it worked fine. Today I occasionally see someone set their whole PC computer system out on the curb, and nobody touches it for a couple of weeks sometimes.
I read years ago that when the new C64 hit the market there were hundreds of thousands of the older VIC20 computers piled up in the warehouses, and nobody wanted them. They all got scrapped.
There's mountains of old electronics thrown out every year and only a small percentage of it has any value to any one, either as scrap or as a collector's item.