it should cost you under $50 bucks as long as you get 1/8 scrap acrylic and somebody to cut it cheap.
To get started you will need several materials:
1.) Acrylic, 1/8" thickness any color of your choice. You will need a 12" by 18" sheet if you cut both pieces or 2 12" by 9" sheets to cut singles.
To screw the 2 acrylic pieces together:
4 Black-Oxide Alloy Steel Socket Head Cap Screw 6-32 Thread, 7/8" Length (these are ones for allen wrenches, you can
use star pattern or regular, my thought the more complicated the screw head the less easily opened)
McMaster Carr # 91251A152
To attach the mount to the back:
4 Flat undercut machine screws 3/4" Screw 6-32 Thread 3/4 Length McMaster Carr # 91099A224
8 Nylon insert Hex Locknut 6/32 Screw 6-32 Thread (these are the zinc grated ones, there are also black ones and
of course you can do nuts without nylon insert) McMaster Carr # 90631A007
4.) Several standoffs:
Aluminum Unthreaded Round Spacer 1/4" OD, 1/2" Length, #6 Screw Size McMaster Carr # 2510A445
Aluminum Threaded Round Standoff 1/4" OD, 1/2" Length, 6-32 Screw Size McMaster Carr # 93330A445
5.) and some bumpers (4 total):
ipad 1: 9/64 inch Adhesive-Backed Polyurethane Bumper Flat Top, 1/2" McMaster Carr #95495K113
ipad 2: 1/4 inch Adhesive-Backed Polyurethane Bumper Flat Top, 1/2" McMaster Carr # 95495K223
6.) a VESA wall mount of your choice. We used this one, it looks ok and cost $17. It is entirely up to you which one you choose.
As far as materials goes, you can use whatever screws you want and you might come up with a better combination all together. Just remember that our file is set for the ones above. You may have to alter the hole sizes in the template if you use different screws. For example, you could use shorter bumpers and reduce the length of your screws and standoffs, etc. All that is up to you.