If someone with experience can look through it, that is the only way I would buy it if I were you. I have 2 Outstanding Criterion Dynamax Telescopes. I also had one that wasn't very good.
A lot of the bad reputation is from the last year of production, they had drained their funds so badly on the lawsuit with Celestron that nobody but the Lawyers Won. EVERYTHING had to go out the door, recently people have been finding that many suffered from poor final assembly, off centered secondary and Correctors. Primary Mirrors mounted on the cells tilted, Zones in the poor float glass in correctors that should have been rejected. Another thing is bad scopes getting sold and resold MANY times on the used Market because they were bad. Also I cant tell you how many people bash them that have NEVER owned or looked through one. That is the one that peeves me. My DX6 is every bit as sharp as my Celestron C6 SCT as a matter of fact I sold the Celestron.
I am familiar with the scope on Ebay (the early Grey one) It has great optics and is as good or better than most Celestron C8's built at the same time. Unfortunately you just never know when a klunker is going to show up.
For students I believe a safer bet would be finding a used Celestron C8. Even most of the Meade 8" SCT's made in the 80's have only fair optics, but you hardly hear anybody bashing them.
If you are only looking for Deep Space only viewing any 8" SCT will work, it is when they have to earn their keep by providing
high power detailed images is where they, fall on their face along with the Meade 2080 (from 1980-1987), and many of the Halley era telescopes.
The scopes being sold for $500.00 that are computerized are probably not going to be the highest quality, A used Celestron NexStar 5, or 6 SE are close to that price. I would stay away from the ETX line, there is just too much plastic for me.