I have consulted the almighty GOOGLE with less than satisfactory results.

I have seen and downloaded the plans for the open source "Freeloader" but at a build price of about $4000 for materials not in my budget.
Some of the basic Mark 10 products would likely work but IIRC somewhere in the $ 1500 range.

Should not be that difficult to build some aluminum extrusion a pair of jaws to hold the material a stepper motor , gears and lead screw.
a load cell to sense force and a HF digital caliper to measure stretch before failure.

And possibly a Dataq DI-145 to handle the data acquisition.

http://www.dataq.com/products/di-145/

With the advent of 3d printers and 3d prosthetics IMHO it would be valuable to have access to material testing.

Tin