You can make your own. Not to highjack the thread but there is a good amount of information in the thread below.
http://geekhack.org/showthread.php?25786-Looking-for-a-keyboard-roof-maybe-make-oneAlso, I recently got a 2 foot line bender. I may start making covers depending on interest. EK's price does seem hard to beat considering you get a final finished product.
In addition to getting the plexiglass (I used a $4 11x14 inch piece of lexan) to make a final product I would have to do the following processes (at least once).
1) Cut to Size (width & length)
2) Polish Edges
3) Bend
I figure I could do all the above but it would take about ~30 (and up to 60 minutes) to get a good looking product. And note that by good looking product it would have to be perfect (smooth edges, no scratches, and a good clean bend/angle). All of those requirements would certainly mean that I would waste a bunch of materials while getting production up and running.
Then there is the point of shipping cost. You would have to be able to do it at a reasonable price. It may not be that bad for a tkl cover but it may be more expensive for a full size cover.
So the question ends up being what would I charge? $20 + S&H? That seems like a decent price from a customer standpoint. That would leave about ~$12 profit after paypal or whoever takes their chunk.
There are a couple of other options I am considering.
Offer custom production process. (Aka. you tell me what you want and I will design it or use your design to build it) Then figure out some fair way to charge people for it. (it would be funny to do something like Cost of Materials + Design Charge + ...
Offer a-la carte pricing - e.g. Price of Material then add $X the bending, add $X for a cut to length, add $X for polishing.
Material - $4
2x 90 degree bend - $5
Cut to Length - $5
Edge polishing - $5
Total - $19 + S&H cost
It would probably work out some funny way to make sure that if you contribute to the GH community through wikis posts/edits, answering questions, etc... you would get reduced pricing or even a pretty cheap product (read: material cost & S/H).
Oh boy, sorry for the WoT!