1000 miles is not a lot of miles for a chain. I do that much in a couple of months and I don't ride nearly as much as some people do. 5-6k is more like it.

Is it rust or dirt? Do you keep the chain lubed? Do you ride a lot in the rain or dirt?

A rusty chain with 1000 miles, that sounds more like you ride it once or twice a month and leave it sit, or store it outside.

Replace this one if you think it necessary, but take care of the new one with a little lube every now and then. Wipe it down if it gets dirty. Put a removable link on it and put it in some cleaner occasionally and relube thoroughly.