Search my post history and you'll find my long thread as a response to someone else.
Now if you are looking for some of the premium quality sheets, these are the list to choose from brand wise.
Sferra
Schlossberg
Christian Fischbacher
Yves Delorme
Pratesi
Frette
Slabbinck
Signoria di Firenze
Of course with any of those, I think the cheapest is the hotel queen set from Pratesi for about $300. It's also not really a good set from them, but the rest of the stuff is outstanding! Of course some of those brands have $1000+ sets of linen so you need buckaroos galore to buy them.
Now, if you are looking for excellent quality for a good price, I can not recommend enough Wamsutta Dream Zone collection. They have them at Bed Bath and Beyond for $189 for a king set. About the lowest price point for what I consider "quality" sheets. Use a 20% coupon and get the price down to $151 before taxes.
Here's a link to them.
http://www.bedbathandbeyond.com/product.asp?SKU=119861
I use these myself. I tried some other department store brands and have several sets like Vera Wang and even some sets off Smart Bargains. They all PALE in comparison to the quality of the higher end sets I have listed in this thread.