I went way off the deep end on pre-orders here in Canada, mainly because companies offered ridiculous pre-order pricing.
1. It's fairly common for Amazon, Best Buy and Wal-mart to run a promo during E3 where almost all pre-orders are 30% off or more.
2. Amazon has historically fucked up and double-applied this promo in some cases (e.g. they lower the item's cost by 30% and then give you an added 30% off of THAT price).
3. Between 2013 and about 2015, the US-CAD exchange rate changed substantially as did expected game prices, slowly creeping up from $60 to $80 in that time span, however a game that was shown at E3 in, say, 2013 or 2014 was up for pre-order at that earlier price (like $60-$70) and effectively locked in.
So this combination meant that it wasn't terribly uncommon for people to get a brand new pre-order edition of a game on day one for like $30 or $40 after taxes, when placing an order a week before release, or buying it off-the-shelf, meant you were paying $92 after taxes. And bear in mind that these orders could still be cancelled with zero penalty prior to shipping, or returned sealed for a full refund, or flipped on craigslist for a profit.
This deal has persisted so I was able to, for example, get Super Mario Odyssey for $57 after taxes when buying it digitally or physically later would have run me $92. The same thing will happen for basically every other new game coming out, I have $57 after-tax preorders for God of War, Red Dead Redemption 2, Days Gone, and a stack of other games expected in 2018.
We don't have Best Buy's GCU, however, and the Amazon Prime discount here is only 10% so I mostly just do a stack of pre-orders during E3, so a game that isn't known to exist at E3 and then comes out before the next E3 misses out on this promo.