I didn't realize AE Conditioner/Cleaner isn't recommended for shell. The description of CC says "Recommended use on Calfskin and other fine leathers", but that's vague. However, I did just find that AE's shell care video specifically mentions it for heavier cleaning.
Any specific reason you don't recommend CC on shell? I do have a small amount of Renovateur, but I figured if I'm going to but stripping over and over, I'd rather use something cheaper if it's still suitable.
For what it's worth, I use both AE cleaner and conditioner and Renovateur on my calfskin shoes, so I'm pretty familiar with both products. Generally, I find that Renovateur does a better job of stripping off the top layer of polish, which is what you are looking to do. I feel like the AE product does a good job cleaning surface dirt and conditioning, but it does not seem to remove as much polish.
With regard to shell, I go back to the warnings about using petroleum based products and other cleaners that are not intended for shell. Would the AE cleaner or conditioner harm your shell shoes? I have no idea, but I wouldn't want to experiment to find out. As has been posted here numerous times, Horween recommends both Venetian Shoe Cream and Renovateur for cleaning and conditioning shell, which seems to be what most here use.
My main point, though, was that the simple act of using a damp rag and brushing the shell will go a long way towards cleaning off the excess polish on the shoes. If you're looking for the cheapest option, this is definitely it - but it will also definitely involve a significant investment of elbow grease.