Well Done!
What kind of condition is the lathe in, operationally? Even if it is worn out there is probably at least $500 worth of parts on it, and the scrap metal value of the rest.
As for the paperwork, what is in the picture appears to be kind of generic stuff that can be found on the Internet so probably not much value there unless you find someone who really prefers the paper copies. Any documentation that pertains to your exact lathe, bill of sale, etc. would help enhance the value of the lathe and shouldn't be separated from it unless the lathe is to be dismantled our scrapped.
Do you plan on keeping and using it? It is probably worth way more than you paid for it (if functional), especially in "machine poor" areas of the country such as the upper great plains.
Please post more pictures and info when you get a chance