From the searching I've done, these appear to be the same supermicro quick rails that work with most of their chassis, and at only $20 USD a set is the cheapest I've ever seen - too bad they want $200 to ship a set to Canada. But maybe someone closer to them can still get them for a reasonable total price.
Repon 2U Rackmount Slide Rails Telescopic Rail Kit SnapServer S2000 E2000 N2000
Repon 2U Rackmount Slide Rails Telescopic Rail Kit SnapServer S2000 E2000 N2000