I would say I spend like $500 a month to run my business which is not bad at all.
November went surprisingly well considering with the holidays my traffic starts to slow down but since I focused on doing a holiday gift guide it helped keep my traffic flowing and get traffic with different keywords instead of my regular keywords I rank with my blog (Product Review Mom). Sometimes you have to step out of the box and do other things on your blog to get new traffic and readers from other niches.
Last month is my highest earnings to date and I'm very proud of my totals!
Here are my November earnings: