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.
Vehicles often sell for much lower than the MSRP (manufacturer suggested retail price). Some car buyers use the dealer price invoice as their target sales price. The invoice price is the price for which the dealer purchased the car from the manufacturer. You can ask a salesperson to show you the dealer price invoice. Or, you can get dealer invoice prices here.