Do a search there have been other threads with lots of speculations. The only variable is the panel. You can save as much as 6 or 7 K if you go with EAB and a simpler panel. I guess paint is also a variable if you paint it or get a pro.
The issue is that "if you go with EAB (experimental amature built) and a simpler panel", you may find you can't get it registered because the RV-12 hasn't been approved under the 51% rule. At that point, it would be pretty expensive yard art until the builder converted it back to the stock configuration for the RV-12 ELSA...
From what I have heard that will not come to pass. I have spoken to a few DARs (and a few have contributed here). The ones I talked to said as long as nothing changes rule wise (and it's unlikely something significant will for now) they would have ZERO problem signing off on a properly built 12 as AB-E (that is an RV-12 with just panel mods and NOT different engines etc...).