If you would like to purchase advertisement space to be placed in the sidebar as a banner or posted as a site review, here are the very cheap prices in US dollars advetisement per month:
Review/blogspost/permanent(written by Admin) = only $10.00
Own Review/blogspost/permanent (guest post) = only $8.00
Sidebar Banner (280×82) = only $10.00
Sidebar Banner (125×125) = only $8.00
Text Link = only $4.00
for statistic, you can view here
For other categories, you can contact the Admin.