the cheapest way, to give for a performance report, then if you need you can recalculate measured value using this report.
140 CAD - I guess, it reasonable cheap, i paid 230 for NIST cert - but they did full re-calibration, said next time it will much expensive ...
usually lab will do calibration with a new constant, if the measure value don't fit in 1year accuracy range. You may ask for 24hours accuracy, if it fit in 140.
Keithley known in inability for one range calibration, need an instruments for a full range , so it kinda difficult for a homemade calibration...