If we use my GK 1001RBII (in a rack case) + 410 RBH stack for an example:
bought both for $700, perfect condition
new it would be $1650.
It cost roughly $80 to get my 1001RBII fully serviced and an output replaced. This has been the only time I've ever brought it in.
When bought used, there is at least the precedent that the product has worked for the last however-many years it has. My stack has been flawless throughout its career, and I take care of it.
When bought new, there may be a factory dud, which actually necessitates warranty. Warranty is nice, but with an $870 discrepancy between new and used, am I really going to drop my head 8 times? Warranty should NOT be the deciding factor, unless you are prone to drop things at every show.
It isn't as much of a gamble as people doom about, buying used.