BenD, the Fish Flash flashers are available in lots of different tackle stores, Big Al's is the manufacturer of the Fish Flash, you can call Big Al's and find out the store closest to you that stocks them.
ROCKFISH, always use a good (ie. Sampo) ball bearing swivel, this will solve most, if not all, of your line twist problems. You can run the Fish Flash off a downrigger, or use a mootching weight, it all depends on what you're trying to do with it and how deep you're trying to fish.
Say you were trying to fish 90ft deep with no downrigger, just use as much weight as you need to get down to the depth you want (maybe 8oz?). With the Fish Flash, unlike Hot Spot-style flashers, because of the way the Fish Flash rotates (on its own axis), you can attach the weight directly to the Fish Flash and it won't impart the action of the flasher.
On the other hand, a Hot Spot-style flasher usually needs at least 6ft or more of line in front of the flasher, to let it rotate correctly... for a given boat speed, the more line in front of the flasher, the slower it rotates, and the shorter the line in front of the flasher, the faster it rotates. Generally, fast rotating flashers are better for coho, and slow rotating flashers are better for chinook.
Now for something completely different... in really shallow fisheries like Chambers creek, John Keizer uses a sliding dropper in front of a Fish Flash. John uses a ball bearing swivel at the end of his line with a bead above it to act like a bumper then above that is a bead chain swivel that has the about 12in of 20lb mono to a snap swivel attached to the weight. This allows a quick weight switch. The ball bearing swivel attaches to the Fish Flash then about 15in of 20b leader with hooks sized to the bait. This way you can keep the gear right on the bottom, where you want it.
-N.