I did 55 gallon water changes every week. Pretty easy. Just gotta stay on top of it. 9,000.00 sounds like too much. I got a 2 year old 750 miracles glass tank for a third of that. So when you say 9,000.00 for a used 600, sounds like crazy talk to me.
But if money isn't an issue for you at all, its pretty convenient to have it ready to go right there.