I bought my Darbee used from a local guy who had tried it and didn't like it. We both have calibrated JVC HD350 projectors, so it really is down to personal taste I'm sure. I paid a little less than the pre price rise price (it was a short drive to collect too, so quicker than waiting to receive it). I wasn't sure if I'd like it, so I knew I could sell it on for a similar price, but I've kept it. Last night I ran a fresh calibration on the HD350/Mini3D combo and forgot to turn the Darbee to 0%. If I get chance later I'm going to run a check to see if I get any differences on or off (I doubt it as others have already tried similar tests) as I want to tweak some colour saturations further anyway.
While I'm glad I bought mine cheaper used, it was more because I was a bit cynical about the device and fully expected to sell it on. However, had I gone to a dealer and demo'd it then I'm sure I would have bought it at the higher price anyway once I saw what it did*
* Caution, I am the same person who put a wanted advert up for a used X30 (RS45) and ended up ordering a brand new X35(RS46), so I'm easily tempted to spend more.