You can create your own designer lampshade. It will look like you paid a lot of money, but it's actually pretty cheap.

All you need is:

a scissors
a long ruler
a sewing machine
great sheet of Tyvek like 100cm x 40cm (39.4 inch x 15.8 inch) or more
some strong yarn
3m with ø1mm (118 inch x 0.04 inch) steel wire
1m with ø4mm (39.4 inch x 0.16 inch) aluminium stick
2 pieces of zip tie

I need a hour to create the lampshape and not more than $20.

Step 1: Cut the Tyvek in Two Pieces

First you need to measure the Tyvek and cut it in two pieces of the same size. Next you have to fold the long side of each piece for 1.5cm (0.6 inch) to a bag.

Step 2: Sew the Pieces Together

Now sew the pieces at the small side together. The stitched side sould be inside of the ring.

Step 3: Sew the Bags

If you have done the ring you can sew the bags for the wire. Fold the long side (two steps before) and sew it together. But let enough space for the wire. You can sew a whole circle but dont close the sew circle, because you need a gap for the wire.

Step 4: Insert the Wire and Add a Stick

When you finished the bags you can insert the wire carefully. Cross the wires to increase stability. Now you can close the bags with the leftover yarn and a needle.

I used a diameter of 64cm (25.6 inch) and fixed the stick and some wire with zip tie together for stability.

Step 5: Mount the Lampshade

For mounting the lampshade you need some wire. Wrap the wire two times around the stick. The ends of the wire will be bend 90 degrees vertical to the stick. This will mount the lampshape on an electric cable. Adjust it at the cable until the lampshape is horizontally aligned.