Originally Posted by MichaelW

The Detours pannier seems to be over-designed and under-built. The mounting system is woefully inadequate.
Any modern pannier mount should comprise at least 2 quick-release, locking hooks that will continue to support even if the lock mechanism breaks. The lower support should be a solid anti-sway hook, not a hook on the end of some elastic or webbing.
Ortleib are about as good as panniers get. You can get similar mounts from Rixen and Kaul which other bag manufactures use (eg the equally good Carradice). You can retrofit R&K mounts to an existing pannier or to a bag that you construct.

If your budget is constrained you may be able to take a standard welded canoe bag of about 30l and rivet or bolt the R&K bracket through an internal stiffener made from correx (corrugated plastic). Fit a correx internal base stiffener with 4 external plastic feet. Carradice have been using this simple attachment method for decades.
Carradice put a mount on a satchel/brief case type bag but the mount is tilted so the bag slopes down, giving more heel clearance.

This is one of the rail systems. Mine uses an aluminium extrusion and sliding hooks for better positioning.