I picked up a 84F from CDI a few months ago. Had it in my hand for $375 including shipping and FFL fees, the latter of which are a little steeper in my area than some places. It has some holster wear but it is completely sound mechanically, and shoots very well.
Two cautions to people who have never owned an 84F: the slide is fairly stiff, and you have to keep the barrel all the way back in the slide as you reassemble the slide to the frame.
The 84F is a nice pistol, though - just nestles right into your hand and feels solid there.
CDI is a well regarded company and was fine to work with. I paid and had my FFL forward their info on the afternoon of the same day the auction ended, and CDI shipped the very next day. The USPS then sent my pistol on an amusing little side trip to San Juan, Puerto Rico, on the way from Kentucky to Florida. I noticed it on the package tracking and emailed CDI. They jumped on it, contacted the postmaster from where they shipped, tracked it, then emailed me after delivery to make sure everything was OK. Really couldn't have asked for any more from them.