I have a 6 month old Celestron mirror diagonal for sale. I have recently gone the route of a focal reducer for my SCT and just have no need for it anymore (I sold my 2" eyepieces as well).
It has worked very well for me and is in excellent condition.
It comes with the original Celestron box and has the 1.25 inch adapter for 1.25 inch eyepieces.
The only blemish is that there are two small scuff marks on the edge of the mirror left by threading the diag. directly into the visual back when I used it with my NexStar8 (so it could clear the base). It has no impact whatsoever on observing as the marks are outside of any field of view. So I never even bothered to even clean the marks off.
$115 which includes shipping anywhere CONUS.
PayPal is OK.