I made $5K in a month with http://textbooksplease.com http://textbooksplease.com (textbook search engine for college students) after spending ~$4K on advertisin

I made $5K in a month with http://textbooksplease.com http://textbooksplease.com (textbook search engine for college students) after spending ~$4K on advertising, but textbook buying only happens twice a year. Re-investing all profit into advertising.