Here's a list of retail stores that will be selling the iPhone 4S on October 14. This is not a complete list, just some suggestions on other places you can go if you don't have an Apple Store near you. All Apple locations will be opening at 8 am local time on Friday, October 14, and will be offering a free Personal Setup service.
AT&T, Verizon and Sprint stores will also be carrying the iPhone 4S, but are not a great option. If you have to buy it directly from your carrier I would call ahead to make sure they plan to have a lot in stock.
The iPhone 4S is $199.99 for the 16GB model, $299.99 for the 32GB model and $399.99 for the 64GB model. All prices require a new or upgraded contract.