Alcohol, somking matter, perfumes and gifts are available on arrival along with a token gesture of other electronics etc but nothing major. You may be able to get someone to price it for you on the way in if you know what you are after though.
Discount is available to airlines that operate through the airport and possibly other majors but ID, as usual, is required. Some of the downtown prices can be very reasonable though, hence the price check comment, but watch out for the guarantee.