probability is about .95 that the 95% confidence interval will include the true population parameter. On the other hand, 2.5% of the time the highest value in the confidence interval will be smaller than the true value, while 2.5% of the time the smallest value in the confidence interval will be greater than the true value.
Set prices with room to move. Most people expect prices at garage sales to be just the starting price and are about 25% to 50% above the seller's (ie your) bottom-line price to allow for negotiating. The amount depends on the condition of the item and how much you are prepared to haggle.
In the beginning of January I went to my local Home Depot for a quote on a garage I would like to build the summer (June, July) I gave them the basics (the size of building, the size and number of windows, size of garage doors, and so on) The quote came in at $17,800 not bad I thought.