You have cpu, memory and Drive upgrades as compared to the current $3000 model. Comparable would be around $4000 CDN
OTOH your RAM is a bit slower, and that 5K monitor on newer models certainly has a major drool factor going for it. Not sure how the GPUs compare. You are off warranty entirely as well.
Every buyer is different, but once it is out of warranty, I am reluctant to spend over half of new. That way even if there are major issues in the very near future, I do not end up spending more than new. I'd try pricing around $2500 and see if it flies. You can always drop a price. Raising it is a lot more difficult.
Did not try finding comparable iMacs pricing, as I am sure you can do that on your own.
Good that you retained the original shipping material, should you be unable to sell locally.
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