Nicole is going to leave her job as an accountant to start up a yoga studio out of her house. She plans to use a guest bedroom that she currently rents out for $400/month. Nicole estimates that it will cost $500 to run the Yoga studio each month. At her accountant job, she makes $5000 per month but expects to make $2000 per month at the Yoga studio. She currently pays $1500 per month to her apartment. What is Nicole's opportunity cost of starting her Yoga studio?