The older Meade ED/APO refractors were known for 2 things: 1) good optics, and 2) notoriously sensitive optical alignment, along with some less-than-stellar post-production "fixes" to some of the cells that made maintaining said alignment very difficult. This had a significant impact to the image in the form of easily visible astigmatism and/or lateral spectral dispersion. Apparently, this was due to the very steep curves Meade needed to use with their glass selections.
I've done significant battle with the 127mm version of the older scopes. The 127's were said to be easier to work on than the 150's, which is pretty spooky. Both of the 127's I worked on needed after market collimatable focusers, and very tedious iterative alignment procedures.
Anyway, I'd proceed with caution: If you don't like to take scopes apart and engage in tedious alignment procedures, I'd avoid the old Meade's, even at really low prices, unless you know for certain that the scope you're interested in doesn't suffer from the above issues. I don't know what year Meade changed their designs, but I bet the one you're looking at is old enough to qualify as the problematic version.
At the price you mention, with a mount to boot, it's very probable there's a problem- that's VERY cheap for a 6" ED/Apo.
Edited by KerryR, 18 April 2019 - 10:28 AM.