I have not had the luck to find a yard sale with fabric, but would be thrilled to find good fabric @ $2.00 a yard. I see it here on the board for $5.00 + a yard with postage on top of that, so $2.00 - $3.00 @ least gives you some bargaining room for those folks that love to barter.
As for the shop-lifting not sure what I would do. It seems hard to believe they both did it by accident, but I would hope that I would say something to them just to let them know it was not okay to just take the items. It's one thing to ask if the prices were negotiable it's another just to take them.