Kid's Planetarium?

Check out amazon.com. They have a lot of different products at various prices. Of course, the ones with the best reviews are around $100. I think the customer reviews on amazon are very helpful. It probably would work best in a totally dark room. Do you have a theater room? I also agree with taking your daughter to some real planetariums like at Fair Park and Richland College, as well at UT Arlington. I am assuming she must have been to some planetarium to even know to ask for one. When my son was about that age, we bought the glow in dark stars and put them all over the ceiling in his bedroom. He loved it!

Maybe get her one you find online and then take her to a "real' planetarium as a fun event.

When I was growing up some of my friends had something like this:

http://www.hearthsong.com/product.asp?pcode=3444&cm%5...

It lit up their room and you could stare at the ceiling. It was pretty cool. This one says for ages 8 and up but maybe you could find another one. Best of luck with your star gazer!

I have been to the Planetarium in University of texas A. Arlington and they have also a great show for kids with elmo and the stars.My baby wasnt even one year old when we went and even he liked the show;)

Updated

My son has been asking for a solar system for awhile since his friend received one for his birthday last Jan. I asked the boys mother which one they had and this is the one,

http://www.toysrus.com/product/index.jsp?productId=273665...

They have had it for close to a year now and they still play with it. We bought it for Christmas.

Hope that helps,
S.