Case in point. The recent release of Mongoose Traveller was sold out in one week. They had to order another printing run. It was completely sold through FLGS's and their online equivalents (see some suggestions below). Amazon, Waterstones, etc. (i.e., the larger companies) haven't yet obtained their copies and are unlikely until next month. Lots of people have therefore canceled their orders and gone to smaller businesses.
Granted, Mongoose have a policy of supporting FLGSs. In fact, if you order something from their web site, they have a message that effectively says, don't buy direct from us, but buy from a FLGS instead.
I of course don't know what will happen in the case of BRP, but it's very, very small business compared to most other things Amazon deal with. I doubt they will be busting a gut to get it in and out as soon as possible. Thus, you may well pay a bit more if you buy it elsewhere, but I suspect you'll get it sooner.
Leisure Games - always have things in asap.
IGUK: Infinity Games UK - Gaming Collectables Board Games CCG TCG Miniatures RPG - sell things often at discount and with free postage
Legendgames - great games, great prices, great service.
Spirit Games, supplying gamers with board games, card games, roleplaying games, d20, wargames and miniatures, for 20 years.
RPG Shop: Role Playing Games, Miniatures, Dice, War Games, Board Games, Paints, and more!
etc.
etc.