That is really weird because i have had nothing but good luck with solen, i got my hivi f6's for 40 CAD and the Ultimax 18 shipped for nearly nothing, I dont have the price off the top of my head, but then again you are far from them in quebec, have you looked into ist and there subs i think they are from manitoba.
EDIT: if the price you are looking at is the best they can do then get a sub from ist, better product then a dayton 8 sub as well.
I recently bought two UM18s through Creative Sound Solutions (http://www.creativesound.ca/). The owner is located near my home, so I just drove to pick them up.
He is reselling from Parts Express, and the warranty / returns would go through him. That means you need to ask him if he has any in stock, or if needs to get any and how long the wait might be.
He sold the UM18-22 for 405 CAD to me, but I did not have to pay shipping. Solen has these listed for 447.60 CAD so a bit more expensive but it maybe has a better reputation, not really sure.
The price from Parts Express is 280 USD (~386 CAD), so I paid about $20 CAD more per driver, but did not have to deal with duty.
I am not sure how much would the shipping be to your place from CSS or Solen, but may be worth checking both.