April you've gotten some great advice here, so I may sound repetitive. Staging costs vary SO much because markets are vastly different from one neighborhood to the next. Each staging job requires different staging help, depending on the house's situation. Because staging jobs vary so much, Professional Stagers have a wide variety of ways to base their fee structures. Some may charge a flat fee for a certain number of rooms, some may charge a percentage of the listing price, some may charge based on square footage, and so on... The staging industry in not regulated, therefore, there really are no standards as of yet. I've seen staging jobs range from $100 DIY Consultation, to $10,000+ Vacant Staging (with furniture rentals, art, etc...). If staging with your own furniture and accessories, you many only need a DIY Consultation from a Stager, which can range typically from $200-$500 for the average home.
I wish the best of luck!