There are several such alternative sites.
http://www.realestate.com/ is one, but no website can give you an “accurate” price for a home. They all offer
estimates. At the end of the day
you (the buyer) are the one who decides what the home is worth. If you think the house is overpriced then move on; there are plenty of other homes to choose from. Zillow is a guide—nothing more. In addition to the figure you get there, look at the asking price from the seller. Then feel free to make them a low ball over. Given the market where you are the seller may bite, say no, or try to negotiate.
Remember Zillow covers the whole country. In some markets it is a very useful tool; in other markets it is of little value. For actual asking sale prices check out realtor.com or ziprealty.com. For foreclosure listings try
http://www.realtytrac.com/. This site offers a free trial period but then you have to subscribe. I am not a fan of realtors but an experienced realtor who has worked with a lot of first time home buyers is what you should be looking for.