Target also sells a standard duvet set for $30 with no frills that you can easily use this technique on.
I've used this technique on my duvets and accent pillows over the years and they have held up great! All you need are pillows and a duvet cover. If you want to go uber cheap, you can pick up 2 standard pillows for about $5 and make your duvet out of two sheets instead (tutorial here). You'll also want to have a ruler, fabric marker (not a sharpie as shown :) ), and a sewing machine. If you don't have a sewing machine, you can follow this technique (tutorial here).
Okay. First step. Turn your pillow/duvet inside out and measure. To get the diamond pintuck, do 3 on top and bottom and 2 in the middle for pillows. For duvets, just make sure the marks are offset. To do the square pintuck like on the white pillows in the above picture, do three rows of the same. I believe I did 5 tucks on each row.
User a yard stick, or a ruler and straight edge (like my valance :) ) to make sure your marks are even. I did not include the opening flap on my measurements since this part usually flaps about on most pillows. Just divide your measurements up by the size of your pillow/duvet. So, if it's 30" and you want 3 tucks, you'll put one at 5", 15" and 25". Two tucks at 30" would be 10" and 20".
Now put each twist into your sewing machine. Sew a few straight lines about a quarter to a half inch in. Now remember, the tighter your twist, the more of a 'pintuck' look you'll get, so try to make your twists hold when transitioning from your hand the sewing machine.
Once you do this to all your marks, it should look like this inside out:
And like this when a pillow is in it:
With the tutorial I mentioned before about the sheet duvet cover and these pillows, you can easily get this look for under $20 :)
Here's a video of the technique in action, filmed a few weeks ago for one of our local lifestyle TV shows: