For me, I will first check the Price Guides in Clubsnap for the items I want to buy. I'll use that as a reference point, then call up a few retailers that are recommended by members in this forum (and that I've had a good experience purchasing from) to get the latest price quotation from them. After they quote me the prices, I'll ask for their name. From there, I'll decide where I want to buy from. If you want to be extra cautious (though I think this is very extreme), walk into the shop and ask for their quotation again, but don't say you called earlier. If they quote you something different, then you ought to get out of there.
It's best to consolidate all your orders and ask for quotations at one go. Sometimes one item is cheaper at A, whilst another item is cheaper at B. Total up the costs for each retailer to see which is the lowest overall.
Also, make sure you know what you want and what you don't want. By that I'm referring to accessories like filters and spare batteries which they may try to promote to you when you're making your purchase. Usually I'll trust the retailers I go to for their recommendations, but at the end of the day, it's a judgment call by the consumer whether to get these additional items that he didn't consider beforehand.
I haven't had any experience of prices fluctuating within a week. From a business' perspective, I think it would be too troublesome to constantly change the price lists, unless it's during a period when a new model is launched or something like that, then you may want to pay more attention.
Hope this helps.
