But just the cost of buying or renting a house / apartment in the SF Bay Area can turn one into a SUPERB trader and 2nd hand shopper. I got my car fixed once through trading with a guy whose kids were having trouble with reading (I taught them to read really well). Etc. I could stretch a dollar like no-one's business....
I still say it's a lot more fun to shop!
This type of "underground" has been going on in San Francisco Bay Area for a lot longer than this Compact group. In my neighborhood we organized a co-op, so to speak: We knew who to borrow a 16ft ladder from. Who had the wheelbarrow, etc. We had annual meetings to discuss this stuff and of course, we had a superb Neighborhood Watch Program. ;>