Depending on exactly where and what features you're looking for expect low $400s at a minimum to close to a mil on the high side, unless you want the deluxe models. Also a few cheaper are out there, down to $250k, but you would have to see if they are suitable for your tastes.
I'll be happy to email you a list of homes with pictures etc... in your price range. Please contact me at 214-289-8555 or email@example.com
I hope this is of some help.
If you need more information contact me for a personal interview...you may qualify for my Realtor's Rebate Program.
Mattye P. Smith
Colonial Real Estate
Another great site to try is http://www.moderndallas.net. It's a great site for all things modern and has a real estate section as well.
Give Classic Urban Homes a call if you are looking for a modern home builder in Dallas!
Coldwell Banker Residantial Brokerage
972-758-2045 Direct Line