First, Amazon offers Daily Deals on their frontpage. It contains million of products. Second, Amazon has Coupon page (see above), make sure you check it before buying. Generally, you can save around $3. Third, Amazon Warehouse offers competitive price on the refurbished product as well.
Shipping is Free for Amazon Prime members which costs $12.99 per month, free 2-day shipping on more than 100 million products. If you are a student, check out student Prime membership. It's 50% off. Individual sellers set their own shipping rates, and free shipping may be offered.
Free if buy from Amazon. It is famous for its easy-return process. Amazon products can be return through UPS or USPS. Just drop it off. Remember, you might have to pay return fee if you buy your item from individual sellers.