$750 sounds legit if the table is in good condition. I don't know about your area, but I shopped around a little when buying mine and I found a few in that price range, but passed on them because they were pretty used. I finally stumbled across the table I ended up buying and I paid ~$1200 for it I believe.
I spent $1100 on the rails, cloth, calibrating the rails and extending them to make 4 1/2" pockets. Now I LOOOOOOOOOOOOOOOOOOOOOOOOVE this table and for a total of $2300.00 there's no way in hell I could be happier. The table plays better than any other I have played on. I should note that I haven't played on a Diamond yet. Until I bought this table I was away from pool altogether for the past few years.