One of the parts places linked above (I think fastlane) has Redline's for $43 a gallon. It's another of the ones that MB hasn't blessed, although RL has a good reputation and their flow specs exceed the MB standards.

When mine again comes due I plan on using the Shell 134 fluid, touted over at BW quite a bit. A few of the members there have used it and reported no problems, smoother shifting, etc. My car doesn't have the drain plug on the torque converter so I will be ordering a case of the fluid, removing the pan to let it drip, then replacing the filter and using the trans pump to flush out the rest of the old fluid through the cooler lines a quart or two at a time.

I do not recall hearing anything negative about Shell 134 fluid.

Like the other poster I've heard noises about the newer Mobil1 134, but have never found it.