In general, yes you can, unless otherwise stated by the author.

Selling the product in a classified ad, and not an auction is very much different than selling it in "Auction", or "Buy it Now".

Please keep in mind that selling a product for .99 is not only devaluing the product for everyone, but it is a 100% guarantee that you will not make enough money from that product to earn yourself any kind of a respectable living. Please price it accordingly.