For an Epson 8700 in good working order $700 is a good price. Does it have any warranty, can you see it run before purchase, can you do without 3D, do you need the excellent lens shift, is the new bulb an OEM lamp and how many true hours on the projector ? If you can answer most of those questions with a yes than its a good buy. The BenQ is a sure thing. Used LCD's with high hours on them tend to have blue panel/diffuser failures and are prone to dust blobs and/or convergence issues. Also some have been known to have short lamp lives.
Smart enough to know better, to old to care