I would say that money is a measure of inefficiency. Say for example you hire a mechanic to fix your car. You pay the mechanic's shop for parts and labor. The cost of parts represents inefficiencies in how they're manufactured, the markups of middlemen, the high cost of raw materials from nonrecycled sources, etc etc. Labor represents your lack of knowledge about how to fix your own car, plus the time involved to fix things on your car like water pumps that (due to uninspired design) fail much earlier than they should.

In an ideal world where you drive a solar-powered car with a dozen moving parts built by robots from recycled materials, costs would fall to a fraction of what they are now. With the same automation applied across all industries, prices would fall to the point where the opportunity cost for humans to be in debt/servitude to rent-seeking financial institutions would exceed the benefit of using money in the first place.

This is basically what happened on Star Trek and is likely to happen in coming decades with Tesla, Amazon etc as humans can no longer compete with machine labor. Things will cost less but incomes will be so low that we won't be able to afford them anyway. Personally I would argue that that started happening sometime after the late 1960s and has gotten to the point where the status quo can only be propped up by every-growing absurdities on a global scale.

An oldie but goodie:

http://marshallbrain.com/manna1.htm