You don't need to buy the whole wrench. All you really need is the liner to fit your frame. A couple of pieces of 1/2 " square steel bar stock from the hardware store( one longer for a handle) drilled for a couple of 1/4" bolts works very well. You can add the pinch bolt if you have to. It ain't as pretty as the MGW wrench, but it is very cheap.
If you are stubborn as well as cheap, you can make a liner. Just cut a strip of cardboard to fit the frame window top to bottom. Place it in the frame window and scribe along the frame on both sides.
You won't be able to scribe the full length, but the balance is pretty easy to sketch in. Now transfer the outline to your liner material ( I use whatever hard plastic I have in the scrap box, cut along the lines and you have a liner. It doesn't have to be an airtight fit.
WOB