There is a 7 days fixed ad discount promo going on at ScarletClicks. For a limited time you can get 7 days fixed ad with the following discounted prices :
10 seconds ad : $28 (from $33)
20 seconds ad : $48 (from $60)
To purchase a fixed ad, you have to go to their 'advertise' page. The exact expiration date of this offer was not mentioned.