One thing I've learned from Canadian retailers is to never trust their online inventory status. It seems Canada lacks the technology to keep online inventory status accurate. Ontario Telescope seems to be the most reliable in this respect, but they're not always 100% accurate.
If it's something you need in a hurry, check with them via phone or email first to ensure that it's in stock.
In addition to the Canadian retailers, a U.S. supplier that I sometimes like to use is B&H Photo. While they're mainly a photography and A/V equipment store, they do have a decent selection of astronomy gear. At checkout, they have an option to collect all duties and taxes up-front. This way, you don't get surprised with dreaded brokerage fees, and you don't have to go to the post office to pay for customs. Shipping is always fast from them when customs are prepaid.
While I naturally prefer to shop Canadian whenever possible, the Canadian retailers often don't carry some of the specialty items I need. Because of that, I wish all the other major US astronomy shops could offer the same customs prepayment option as B&H. Are you U.S. retailers listening?
Edited by ecorm, 23 February 2021 - 11:40 PM.