I think you had the key point right in your post. You have been taking them in the States. How many people offer courses of his caliber (pardon the pun) here in Canada? Some of it I'm sure had to do with overhead costs being higher. Range availabilities, ammo costs are higher here, gun rentals (PGW Coyote?!) and the fact that we have a much smaller demographic of people to keep a business like that steady. For his super long range courses, I heard he runs them at the DND range all the way out to 1800m. That doesn't come free. I was looking at taking his 7 day 1800m, but in the end, it was something like 2k plus 400 rounds of my .338 Improved ($400) plus 7 days off work, plus spinning on a new barrel cause that would have been the end of it. All said and done, I would have been done at nearly 4k. Im sure I would have learn a TON, but not in my budget this year.
You have to remember, this guy held the world record confirmed kill for a while. WORLD RECORD. Not many people get an opportunity to learn from someone with those capabilities in their backyard. Some would say that earns a premium. I don't really see how $300 for a day course is high either. A 2 day carbine course with all your own gear is usually about $450. The OP said he rented all the kit.
Not really sure you have taken as many courses as you profess from all the "Navy Seals" and "Green Berets" and "Black Water" mall ninjas.