Plano & Los Colinas are a couple of really nice places to live.
Plano is north of Dallas (just north of Richardson, aka 'telecom corridor') and much nicer than Richardson, IMHO.
Los Colinas is is nicer part of Irving (close to everything, really).
Dunno about prices on buying houses, since I rent but I've heard $200,000 for a nice place in Los Colinas or Irving. (but don't take my word for it, I'm just talking out of my ass)