Not much to be honest, but there are many things which can decrease or increase what it's worth. Does the keyboard work? Is the box and packaging in good condition? Does the computer work? How's the video output? What about the keyboard?
Some collectors look for the original stuff only and will pay more for something that is complete and in good cosmetic condition and working. Others are only interested in the working condition and don't care that much if it's boxed or not. Others only care about the working condition and modifications so that they can use it with a modern TV, etc.
If it's complete and looks nice but some of the keys don't work, most people won't be interested. If it's not complete but it's an upgraded ZX81 or at least tested as working, it's interesting to some. There are too many variables.
Here in the U.S. it's still possible to buy one in kit form (from Zebra Systems) but I find it too expensive.
I recommend visiting the ZX81 forums too if you haven't done so already.
Comments
Some collectors look for the original stuff only and will pay more for something that is complete and in good cosmetic condition and working. Others are only interested in the working condition and don't care that much if it's boxed or not. Others only care about the working condition and modifications so that they can use it with a modern TV, etc.
If it's complete and looks nice but some of the keys don't work, most people won't be interested. If it's not complete but it's an upgraded ZX81 or at least tested as working, it's interesting to some. There are too many variables.
Here in the U.S. it's still possible to buy one in kit form (from Zebra Systems) but I find it too expensive.
I recommend visiting the ZX81 forums too if you haven't done so already.
I guess the best thing to do is stick it on ebay and see what it gets if I decide to sell.
Cheers Pete.