I have to agree with @valance
What age group are you targeting?
Whilst typing this i noticed that most of your ads are for the younger generation so possibly the use of soft pastel yellows and reds might do the trick
Maybe a soft pastel yellow background with a soft pastel right sidebar background with maybe the same red for when people hover over the adverts
Then with your header logo maybe change the colours from dark to light or maybe red and yellow again and make it fit the whole width of the page
The possibility of dropping the search bar below the featured listings
Also maybe the use of the ACFCP Plugin might help with displaying "Ad Specifications" like here
http://acfcp.codedforest.com/ads/ferrari-prototype/ displaying key features of each product
"Only giving you suggestions and options" it may help
Regards Chris