Thank you for helping us improve the quality of Unity Documentation. Although we cannot accept all submissions, we do read each suggested change from our users and will make updates where applicable.
CloseAssets can be submitted into the daily deals at the Asset Store Sales Signup page.
You are able to change the price of your asset for your own promotions; however the promotion must be advertised by your own means such as a forum post. If you decide to change the key images, then this must be discrete and not too over the top.