Unlike other brands of sheets, brands of Egyptian cotton sheets are most definitely not a dime a dozen. Facts are that you're not going to find real high quality Egyptian cotton sheets in stores like Wal-Mart or Target. You probably can't even find real high quality sets at Bed Bath & Beyond.
Where you can find them is at high end designer department stores such as Neiman Marcus, Nordstrom, and Saks Fifth Avenue. They're typically available at both the brick & mortar stores and at the websites of these retailers.
These stores only carry reputable brands of Egyptian cotton sheets, because carrying anything less would damage their own reputations. Considering the fact that these companies are decades old and are frequented by people that makes hundreds of thousands of dollars a year or more, that's not something that they're going to risk. luxuryofthepharaohs.com has some more affordable brands here.
Some popular brands of Egyptian cotton sheets are Signoria Firenze, Stokke, Sferra, and Matouk. Be warned, though; you're going to spend hundreds of dollars on a single set of any of these, unlike some sets that you can find at luxuryofthepharaohs.com . Some sets of pillow cases alone can run into the hundreds of dollars.
You're better off going with a set that's going to cost you a pretty penny, though, than you are grabbing yourself some fake $60 Egyptian cotton sheets at Wally World.