If the telescope is in good condition and all that is required is to clean the mirror then there is no problem,just depends what he means by "cleaning"?
Ask him to send the photo's and publish them on here to give us some idea as to what the state of the mirror is.
If the telescope has had very little use and the mirror has no mold then I see nothing wrong in buying it at that price.
A 10" mirror could cost upto about $400:00 to recoat depending who you get to do it?
Cleaning is very easy and instructions are available on this site.
Cheers
