Welcome to the CPMF Bodger.
It is difficult to say what your HBR 0123456 ladder is worth without a scan/picture attached to your enquiry.
Your description of "near-mint" is a term more fitting for coins than polymer notes & the condition of your note is the most important factor determining its value. If your note is Almost Uncirculated (AU for short) than it would book at $400 (a figure based on 80% of the $500 BV in the 2016th Ed of Charlton's Canadian Government Paper Money). Keep in mind this is strictly a "ballpark estimation" and doesn't mean that is what the market will bear if you decide to sell the ladder note (it could be more/could be less).
If you have other special serial numbers you could either go to the library and check them in the Charlton guide mentioned above (or purchase a copy).
Hope this helps (& great note btw).
W2W
