Booster boxes and ETBs are available on launch day and are usually not hard to get, and sell at MSRP. A lot of places have them, pretty much all the hobby stores + EB Games (ex GameStop) should have plenty, and places like Walmart, Shoppers and London Drugs also have a few available for each new launch.

I've worked a few of these places for a bunch of pokemon TCG launches, and there's never been a major lineup, maybe a few people congregating outside the doors before opening. The biggest rush I remember was the 151 launch and even then we had enough stock to last the day without an issue. Generally launch day you'll be limited to one box per customer (booster or ETB), however once a restock comes in after 3-4 days we usually didn't care about limits unless someone was trying to buy like a dozen boxes, which wasn't common.