I also think that the general fabric of laws, ideologies, and customs --- which corresponds to economic prices --- is much more nearly objective and universal.
This is the crux of the matter. I have two issues with that.
1. When two cultures have different views about what is right or wrong, how do you objectively judge between them?
I have a good answer for this (which corresponds to the way economic prices are set). With cultural relativity each society responds to unique circumstances and factors to come up with a value system that works for them. Diamonds have no universal value (most things in the Universe have no use for diamonds) but we as modern western human beings have decided they are valuable in a way that works for us (and clearly human beings in different circumstances would assign a different value to diamonds and some may assign no more value to them then any other rock).
I don't know how to find a "general fabric of laws..." that explains the extreme differences in moral laws that has existed between human cultures throughout history. This really is the biggest problem with moral absolutism.
2. You still haven't suggested what gives this proposed "general fabric of laws, ideologies and customs" any intrinsic value, especially given the fact that there have been successful (in the evolutionary sense) cultures with wildly different ideas of laws, ideologies and customs.