Lizshawna,
Another option is a broker price opinion (BPO). Similar to an appraisal, but done by a real estate agent rather than an appraiser. Maybe no charge if you're thinking of listing the property with the agent, or if you have a working relationship. The appraisal will be more detailed, and should be more accurate.
All those assume you have a house you're ready to sell. If you mean you're looking at fixers to buy and rehab, its a little more complex. You probably don't want to drive an agent nutty doing multiple BPOs and you certainly don't want to pay $400 for every house you consider. If this is your situation, you need to get out and get to know the area you're working. Go to open houses, look at listed houses, and talk to agents. There are various sources of data, including agents, title companies, public records, and even online services like zillow. Once you've looked at enough properties in an area, you'll get a feeling for what properties sell for, and be able to come up with a pretty accurate estimate yourself. That will allow you to determine which properties are worth taking to the next level and doing a BPO or an appraisal.
Jon